Energy Harvesting & Wing Morphing Design Using Piezoelectric Macro Fiber Composites

Energy harvesting from vibration sources was a very promising field of research throughout the last few decades among the engineers and scientist as considering the necessity of renewable/green energy for the welfare of mankind. Unused vibration energy exists in the surrounding or machineries was always tried to be utilized. Since then, by using piezoelectric transduction, researchers started to harvest the vibration energy. However, after the invention of piezo ceramics Macro Fiber Composites (MFC) by NASA, the research in this field augmented a lot due to its high efficiency to convert mechanical strain or vibration to useful electrical power and vice versa. Apart from energy harvesting researcher concentrated to utilize this harvested energy for daily life and hence application of this harvested energy for structural health monitoring inaugurated. Recent study showed that, the vibration energy harvested from the vehicles or aerospace (UAV) structure is good enough to power its onboard structural health monitoring unit though for feeding this power to any other onboard electrical system is still challenging due to low power generation along with its random production. Moreover, Macro Fiber Composites (MFC) can be used as an actuator to change the shape of aircraft wing to enhance aerodynamic performance and hence, application of MFC for wing morphing design has become popular throughout these years. The purpose of this research work is to depict the recent progress & development that took place in the field of energy harvesting & wing morphing research using macro fiber composites and combining the existing knowledge continue the work further, the future of this harvested energy, new design concept & upcoming challenges along with its possible solution. This work investigates the different configuration of macro fiber composites (MFC) for piezoelectric energy harvesting and its contribution for wing morphing design with enhanced aerodynamics. For the first part of this work, uniform MFC configuration was modeled and built up based on the Euler-Bernoulli beam theory. When the governing differential equations of the systems were derived, by applying the harmonic base excitation, coupled vibration response and the voltage response were obtained. The prediction of the mathematical model was at first verified by unimorph MFC with a brass substrate obtained from the state of art and then validation was justified by MFC unimorph along with three different substrate materials (copper, zinc alloy & galvanized steel) and thickness for the first time in this type of research. Computational & analytical solution revealed that, among these three substrates and for same thickness, maximum peak power at resonance excitation was obtained for the copper substrate. For the second part of the study (i) computational analysis was performed and the output was compared with the real time data obtained from the wind tunnel experiment and the conclusion stood that, with the increment of the incoming flow velocity, the power output from the MFC increases with a thin aerofoil made of copper substrates and two MFC on its upper surface (ii) wing morphing design was performed for a NACA 0012 aerofoil for the first time where macro fiber composite actuators were used to change the top and bottom surfaces of the aerofoil with a view to recording the enhanced aerodynamics performance the designed morphing wing. CFD simulation results were compared with the wind tunnel testing data from the state of art for NACA 0014 for all identical parameters. The enhanced aerodynamics performance observed for designed wing morphing can be used for future concepts like maneuvering of the aircraft without the help of ailerons or for the purpose of active flow control over the aircraft wing

Diagnosed with primary adrenal insufficiency? search adrenoleukodystrophy-two brothers presented with similar phenotype

X-linked adrenoleukodystrophy (X-ALD) is a genetic disease with a variety of phenotypic expression. This is the first case report of X-AMN/ALD in two brothers in Bangladesh confirmed by raised VLCFA. Our index patient of 19 years presented on 2014 with adrenal insufficiency, after one year developed progressive spastic paraparesis along with cognitive declination and behavioral abnormality. His only brother was clinically asymptomatic at presentation with Addison’s disease and extensor planter reflexes. After three years of follow up, index patient became bed bound with slurred speech, urinary urge incontinence and his brother developed spastic paraparesis with cognitive impairment. None had gonadal impairment. Follow up MRI after three years revealed lesion in brainstem in both along with atrophy of thoracic segment of spinal cord in index patient and cerebellum, internal capsule involvement in his brother. Both were of pure AMN variety but due to presence of cognitive impairment and behavioral abnormality they can be categorized as cerebral variety of AMN. On 2023, our index patient is still surviving with major functional disability and his brother died on 2019, 5 years of initial diagnosis

When experiencing discrimination predicts greater outgroup affiliation:The role of intergroup mobility in moderating rejection-(Dis)identification patterns

Research has documented how groups cope with perceived discrimination by enhancing their identification with their minority ingroup and reducing their identification with the majority outgroup. However, these patterns have not been consistent across contexts nor examined in relation to discrimination encountered online. Through a survey of PRC Chinese immigrants in Singapore, we examine how online perceived discrimination relates to attitudes toward the Singaporean host society via both ingroup and outgroup identification. We also test the role of intergroup mobility, the perceived level of opportunity ingroup members have to form relationships with dominant outgroup members, as a moderator of these relations. Results show that PRC Chinese immigrants who perceived more discrimination online identified more strongly with both their PRC Chinese ingroup and the Singaporean host society outgroup. In turn, greater PRC Chinese and Singaporean identification related to more positive attitudes toward Singaporeans. Moreover, intergroup mobility moderated these associations, such that the PRC Chinese who perceived greater mobility were more likely to strengthen their identification with Singaporeans as their online perceived discrimination increased. We argue that intergroup mobility beliefs may play a key role in shaping defensive responses to perceived discrimination.</p

Patterns of post endoscopic retrograde cholangiopancreatography (ERCP) complications- experience from an university hospital

In the treatment of common bile duct stones and palliative decompression of malignant strictures, endoscopic retrograde cholangiopancreatography (ERCP) is the gold standard. However, there are still concerns about procedure-related complications and patient discom- fort. To evaluate the pattern of the post ERCP complications. This prospective observational study was conducted at the Department of Gastroenterology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka from February 2017 to October 2017. A total of one hundred patients who were eligible for ERCP were included in this study but five patients were excluded due to cannulation failure. Clinical examination , biochemical, and radiological investigation were performed before and after ERCP to assess the complication that occurred. The majority of patients in this study were under the age of 50, with a mean age of 49.74 }14.07 years between the ages of 18 and 80 years. Males (54.7%) were predominant than female (45.3%) and male to female ratio was 1.21:1. The most common diagnosis was choledocholithiasis (58.9%) followed by proximal cholangiocarcinoma (13.7%), Carcinoma-gallbladder with biliary infiltration (8.4%), Distal cholangiocarcinoma (6.3%), Chronic calcific pancreatitis and Periampullary carcinoma each (3.2%), Suspected SOD &amp; Chronic pancreatitis each (2.1%) and Worm in CBD and benign biliary stricture each (1.1%). In this study, the overall post-ERCP complication rate was 12.6% with pancreatitis accounting for 9.4%, bleeding accounting for 2.1%, and cholangitis accounting for 2.1%. From the study data it can be concluded that pancreatitis is the most frequent Post-ERCP complication. BSMMU J 2022; 15(1): 50-5

A Move Towards Focused Parathyroidectomy in BSMMU Even Under Local Anesthesia

Parathyroidectomy needs skill and experience for its tiny size and variation in number and location. The retrospective quasi-experimental study of 26 parathyroid operations was done in endocrine surgery unit of BSMMU during October 1994 to March 2007. All patients were within 31 to 50 years of age with female preponderance (M:F=1:5.5). All the patients had primary hyperparathyroidism diagnosed biochemically with variable rise of serum calcium and serum intact parathormone level and finally proved as single parathyroid adenoma after surgery. Different preoperative localization tests were done in 22 patients with positive impression in all except 2 (7.69%) sestamibi scan. The sestamibi scan showed 50% (2/4) negative impression which, later on, was proved as 100% false negative at surgery. Bilateral neck exploration (BNE) was done on 18 patients with 94.44% success of surgery and &lsquo;focused' parathyroidectomy by unilateral neck exploration (UNE) was done on 7 patients of whom 4 underwent local anaesthesia with 100% success of gland removal. Temporary postoperative hypocalcaemia was observed in 22 patients. Full recovery from hypocalcaemia was in 20 (90.90%) patients though 2 (7.69%) patients with late diagnosis showed irreversible outcome not due to surgery but due to postoperative complex renal and cardiovascular deterioration. Focused parathyroidectomy can be safely done even under local anaesthesia in tertiary hospital. Key words: Primary hyperparathyroidism; preoperative localization; focused parathyroidectomy; local anaesthesia.DOI: 10.3329/bsmmuj.v2i1.3708 BSMMU J 2009; 2(1): 31-3

Levels, trends, and inequalities in using institutional delivery services in low- and middle-income countries: a stratified analysis by facility type

Introduction: To ensure equitable and accessible services and improved utilization of institutional delivery it is important to identify what progress has been achieved, whether there are vulnerable and disadvantaged groups that need specific attention and what are the key factors affecting the utilization of institutional delivery services. In this study, we examined levels, trends, and inequalities in the utilization of institutional delivery services in low- and middle-income countries. Methods: We used nationally representative cross-sectional data from Demographic and Health Surveys (DHS) conducted during 1990–2018. Bayesian linear regression analysis was performed. Results: Among 74 countries, the utilization of institutional delivery services ranged from 23.7% in Chad to 100% in Ukraine and Armenia (with >90% in 19 countries and <50% in 13 countries) during the latest DHS rounds. Trend analysis in 63 countries with at least 2 surveys showed that the utilization of institutional delivery services increased in 60 countries during 1990–2018, with the highest increase being in Cambodia (18.3%). During this period, the utilization of institutional delivery services increased in 90.3% of countries among the richest, 95.2% of countries in urban, and 84.1% of countries among secondary+ educated women. The utilization of institutional delivery services was higher among wealthiest, urban, and secondary+ educated women compared to their counterparts. Greater utilization of private facilities for delivery was observed in women from the highest income group and urban communities, whereas highest utilization of public facilities was observed for women from the lowest income group and rural communities. Conclusions: The utilization of institutional delivery services varied substantially between and within countries over time. Significant disparities in service utilization identified in this study highlight the need for tailored support for women from disadvantaged and vulnerable groups

Modeling of mixed-solvent electrolyte systems

International audienceModels for mixed-solvent strong electrolytes, using an equation of state (EoS) are reviewed in this work. Through the example of ePPC-SAFT (that includes a Born term and ionic association), the meaning and the effect of each contribution to the solvation energy and the mean ionic activity coefficient are investigated. The importance of the dielectric constant is critically reviewed, with a focus on the use of a salt-concentration dependent function. The parameterization is performed using two adjustable parameters for each ion: a minimum approach distance () and an association energy (). These two parameters are optimized by fitting experimental activity coefficient and liquid density data, for all alkali halide salts simultaneously, in the range 298K to 423K. The model is subsequently tested on a large number of available experimental data, including salting out of Methane/Ethane/CO 2 /H 2 S. In all cases the deviations in bubble pressures were below 20% AADP. Predictions of vapor-liquid equilibrium of mixed solvent electrolyte systems containing methanol, ethanol are also made where deviations in bubble pressures were found to be below 10% (AADP)