Search results for: Abhishek Tiwari

Authors: Dinesh Munjurulimana, Anil Tiwari, Tingwen Li, Carlos Pereira, Sreekanth Pannala, John Waters

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With the rapid transition to electric vehicles (EVs) across the globe, car manufacturers are in need of integrated and lightweight solutions for the battery packs of these vehicles. An integral part of a battery pack is the battery tray, which constitutes a significant portion of the pack’s overall weight. Based on the functional requirements, cost targets, and packaging space available, a range of materials –from metals, composites, and plastics– are often used to develop these battery trays. This paper considers the design and development of integrated thermoplastic-intensive battery trays, using the available packaging space from a representative EV battery pack. Presented as a proposed alternative are multiple concepts to integrate several connected systems such as cooling plates and underbody impact protection parts of a multi-piece incumbent battery pack. The resulting digital prototype was evaluated for several mechanical performance measures such as mechanical shock, drop, crush resistance, modal analysis, and torsional stiffness. The performance of this alternative design is then compared with the incumbent solution. In addition, insights are gleaned into how these novel approaches can be optimized to meet or exceed the performance of incumbent designs. Preliminary manufacturing feasibility of the optimal solution using injection molding and other commonly used manufacturing methods for thermoplastics is briefly explained. Then numerical and analytical evaluations are performed to show a representative Pareto front of cost vs. volume of the production parts. The proposed solution is observed to offer weight savings of up to 40% on a component level and part elimination of up to two systems in the battery pack of a typical battery EV while offering the potential to meet the required performance measures highlighted above. These conceptual solutions are also observed to potentially offer secondary benefits such as improved thermal and electrical isolations and be able to achieve complex geometrical features, thus demonstrating the ability to use the complete packaging space available in the vehicle platform considered. The detailed study presented in this paper serves as a valuable reference for researches across the globe working on the development of EV battery packs – especially those with an interest in the potential of employing alternate solutions as part of a mixed-material system to help capture untapped opportunities to optimize performance and meet critical application requirements.

Keywords: thermoplastics, lightweighting, part integration, electric vehicle battery packs

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Authors: Ilham Zaidi, P. Sankara Sarma, Quazi Taufique Ahmed, V. Raman Kutty, Khalid Umer Khayyam, Gurpreet Singh, Abhishek Royal

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Introduction: Tuberculosis is a global public health emergency, but it is particularly acute in India, which has the world's highest tuberculosis burden. Due to overpopulation, lack of sanitation, malnutrition, low living standards, and poor socioeconomic status, among other factors, it is India's most common infectious disease. The long period of treatment is one of the main reasons for considering it as a public health emergency. Consequently, there is an increase in patient noncompliance, which leads to treatment failure, adverse treatment outcomes, and deaths. This could lead to the growth of anti-TB drug resistance. According to the WHO, approximately 558 thousand new cases of Multi-Drug Resistance Tuberculosis were diagnosed worldwide, with 8.5 percent developed Extensively Drug Resistance Tuberculosis. Methodology: This study is a program-based cross-sectional descriptive survey of adult tuberculosis patients enrolled in the Delhi-based Revised National Tuberculosis Program. The study setting was 27 NTEP districts of Delhi. (N=65,893) and Sample size- was 200; the sampling method which is used in the study was the systemic random sampling method. Results: Most of the demographic factors (age, gender, residence, and family type) were not significantly associated with adherence; marital status was found statistically significant with the treatment compliance. Hesitation while telling people about the disease and motivation to strictly follow drug schedule by healthcare workers were other factors where a significant association with drug adherence was observed. The study findings also suggest that provision of food, minimal financial and other moral support from family, counseling, discussion and politeness by healthcare providers might also facilitate adherence. Discussion and Conclusions: For TB treatment, adherence, age, sex, socioeconomic status, types of accommodations, malnutrition, and personal hygiene should all be considered; similar results were observed in previous studies. In the care of TB patients, DOTS services, health workers, and family support play a significant role. According to the country's National Strategic Plan, the Indian government has set a goal of eliminating tuberculosis by 2025 and patients' compliance with TB care and treatment adherence is very crucial to achieve this aim. A cohort study will be able to give a better understanding of factors associated with adherence since this study may have missed some defaulters who were absconding and could not be reached. Important Terms: RNTCP, NTEP, DOTS, DS-TB, DR-TB, RR-TB, MDR-TB, XDR-TB, Treatment failure, Treatment relapse, Treatment adherence.

Keywords: treatment adherence, treatment relapse, treatment failure, drug resistance tuberculosis

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Authors: Bibha Kumari, Nigel P. Brunton, Dilip K. Rai, Brijesh K. Tiwari

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Edible mushrooms possess numerous functional components like homo- and hetero- β-glucans [β(1→3), β(1→4) and β(1→6) glucosidic linkages], chitins, ergosterols, bioactive polysaccharides and peptides imparting health beneficial properties to mushrooms. Some of the proven biological activities of mushroom extracts are antioxidant, antimicrobial, immunomodulatory, cholesterol lowering activity by inhibiting a key cholesterol metabolism enzyme i.e. 3-hydroxy-3-methyl-glutaryl CoA reductase (HMGCR), angiotensin I-converting enzyme (ACE) inhibition. Application of novel extraction technologies like pulsed electric field (PEF) and high power ultrasound offers clean, green, faster and efficient extraction alternatives with enhanced and good quality extracts. Sequential PEF followed by ultrasound assisted extraction (UAE) were applied to recover bioactive enriched fractions from industrial white button mushroom (Agaricus bisporus) stalk waste using environmentally friendly and GRAS solvents i.e. water and water/ethanol combinations. The PEF treatment was carried out at 60% output voltage, 2 Hz frequency for 500 pulses of 20 microseconds pulse width, using KCl salt solution of 0.6 mS/cm conductivity by the placing 35g of chopped fresh mushroom stalks and 25g of salt solution in the 4x4x4cm3 treatment chamber. Sequential UAE was carried out on the PEF pre-treated samples using ultrasonic-water-bath (USB) of three frequencies (25 KHz, 35 KHz and 45 KHz) for various treatment times (15-120 min) at 80°C. Individual treatment using either PEF or UAE were also investigation to compare the effect of each treatment along with the combined effect on the recovery and bioactivity of the crude extracts. The freeze dried mushroom stalk powder was characterised for proximate compositional parameters (dry weight basis) showing 64.11% total carbohydrate, 19.12% total protein, 7.21% total fat, 31.2% total dietary fiber, 7.9% chitin (as glucosamine equivalent) and 1.02% β-glucan content. The total phenolic contents (TPC) were determined by the Folin-Ciocalteu procedure and expressed as gallic-acid-equivalents (GAE). The antioxidant properties were ascertained using DPPH and FRAP assays and expressed as trolox-equivalents (TE). HMGCR activity and molecular mass of β-glucans will be measured using the commercial HMG-CoA Reductase Assay kit (Sigma-Aldrich) and size exclusion chromatography (HPLC-SEC), respectively. Effects of PEF, UAE and their combination on the antioxidant capacity, HMGCR inhibition and β-glucans content will be presented.

Keywords: β-glucan, mushroom stalks, pulsed electric field (PEF), ultrasound assisted extraction (UAE)

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Authors: Abhishek Sharma, Arnab Banerjee

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The research is intended to study the solar electric propulsion (SEP) technology for planetary missions. The main benefits of using solar electric propulsion for such missions are shorter flight times, more frequent target accessibility and the use of a smaller launch vehicle than that required by a comparable chemical propulsion mission. Energized by electric power from on-board solar arrays, the electrically propelled system uses 10 times less propellant than conventional chemical propulsion system, yet the reduced fuel mass can provide vigorous power which is capable of propelling robotic and crewed missions beyond the Lower Earth Orbit (LEO). The various thrusters used in the SEP are gridded ion thrusters and the Hall Effect thrusters. The research is solely aimed to study the ion thrusters and investigate the complications related to it and what can be done to overcome the glitches. The ion thrusters are used because they are found to have a total lower propellant requirement and have substantially longer time. In the ion thrusters, the anode pushes or directs the incoming electrons from the cathode. But the anode is not maintained at a very high potential which leads to divergence. Divergence leads to the charges interacting against the surface of the thruster. Just as the charges ionize the xenon gases, they are capable of ionizing the surfaces and over time destroy the surface and hence contaminate it. Hence the lifetime of thruster gets limited. So a solution to this problem is using substances which are not easy to ionize as the surface material. Another approach can be to increase the potential of anode so that the electrons don’t deviate much or reduce the length of thruster such that the positive anode is more effective. The aim is to work on these aspects as to how constriction of the deviation of charges can be done by keeping the input power constant and hence increase the lifetime of the thruster. Predominantly ring cusp magnets are used in the ion thrusters. However, the study is also intended to observe the effect of using solenoid for producing micro-solenoidal magnetic field apart from using the ring cusp magnetic field which are used in the discharge chamber for prevention of interaction of electrons with the ionization walls. Another foremost area of interest is what are the ways by which power can be provided to the Solar Electric Propulsion Vehicle for lowering and boosting the orbit of the spacecraft and also provide substantial amount of power to the solenoid for producing stronger magnetic fields. This can be successfully achieved by using the concept of Electro-dynamic tether which will serve as a power source for powering both the vehicle and the solenoids in the ion thruster and hence eliminating the need for carrying extra propellant on the spacecraft which will reduce the weight and hence reduce the cost of space propulsion.

Keywords: electro-dynamic tether, ion thruster, lifetime of thruster, solar electric propulsion vehicle

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Authors: Abhishek Sraw, Amit Sobti, Yamini Pandey, R. K. Wanchoo, Amrit Pal Toor

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Monocrotophos (MCP) is a widely used pesticide in India, which belong to an extremely toxic organophosphorus family, is persistent in nature and its toxicity is widely reported in all environmental segments in the country. Advanced Oxidation Process (AOP) is a promising solution to the problem of water pollution. TiO₂ is being widely used as a photocatalyst because of its many advantages, but it has a large band gap, due to which it is modified using metal and nonmetal dopant to make it active under sunlight and visible light. The use of nanosized powdered catalysts makes the recovery process extremely complicated. Hence the aim is to use low cost, easily available, eco-friendly clay material in form of bead as the support for the immobilization of catalyst, to solve the problem of post-separation of suspended catalyst from treated water. A recirculation type photocatalytic reactor (RTPR), using ultraviolet light emitting source (blue black lamp) was designed which work effectively for both suspended catalysts and catalyst coated clay beads. The bare, TiO₂ and W-TiO₂ coated clay beads were characterized by scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS) and N₂ adsorption–desorption measurements techniques (BET) for their structural, textural and electronic properties. The study involved variation of different parameters like light conditions, recirculation rate, light intensity and initial MCP concentration under UV and sunlight for the degradation of MCP. The degradation and mineralization studies of the insecticide solution were performed using UV-Visible spectrophotometer, and COD vario-photometer and GC-MS analysis respectively. The main focus of the work lies in checking the recyclability of the immobilized TiO₂ over clay beads in the developed RTPR up to 30 continuous cycles without reactivation of catalyst. The results demonstrated the economic feasibility of the utilization of developed RTPR for the efficient purification of pesticide polluted water. The prepared TiO₂ clay beads delivered 75.78% degradation of MCP under UV light with negligible catalyst loss. Application of W-TiO₂ coated clay beads filled RTPR for the degradation of MCP under sunlight, however, shows 32% higher degradation of MCP than the same system based on undoped TiO₂. The COD measurements of TiO₂ coated beads led to 73.75% COD reduction while W-TiO₂ resulted in 87.89% COD reduction. The GC-MS analysis confirms the efficient breakdown of complex MCP molecules into simpler hydrocarbons. This supports the promising application of clay beads as a support for the photocatalyst and proves its eco-friendly nature, excellent recyclability, catalyst holding capacity, and economic viability.

Keywords: immobilized clay beads, monocrotophos, recirculation type photocatalytic reactor, TiO₂

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Authors: Ashwini Tiwari

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Introduction: Inclusive education for all is a multifaceted approach that requires system thinking and the promotion of a "Culture of Inclusion." Such can only be achieved through the collaboration of multiple stakeholders at the community, regional, state, national, and international levels. Researchers have found effective practices used in inclusive general classrooms are beneficial to all students, including students with disabilities, those who experience challenges academically and socially, and students without disabilities as well. However, to date, no statistically significant effects on the academic performance of students without disabilities in the presence of students with disabilities have been revealed. Therefore, proponents against inclusive education practices, based solely on their beliefs regarding the detrimental effects of students without disabilities, appears to have unfounded perceptions. This qualitative case study examines students' perspectives and beliefs about inclusive education in a middle school in South Texas. More specifically, this study examined students understanding of how inclusive education practices intersect with the classroom community. The data was collected from the students attending fully inclusive classrooms through interviews and focus groups. The findings suggest that peer integration and friendships built during classes are an essential part of schooling for both disabled and non-disabled students. Research Methodology: This qualitative case study used observations and focus group interviews with 12 middle school students attending an inclusive classroom at a public school located in South Texas. The participant of this study includes eight females and five males. All the study participants attend a fully inclusive middle school with special needs peers. Five of the students had disabilities. The focus groups and interviews were conducted during for entire academic year, with an average of one focus group and observation each month. The data were analyzed using the constant comparative method. The data from the focus group and observation were continuously compared for emerging codes during the data collection process. Codes were further refined and merged. Themes emerged as a result of the interpretation at the end of the data analysis process. Findings and discussion: This study was conducted to examine disabled and non-disabled students' perspectives on the inclusion of disabled students. The study revealed that non-disabled students generally have positive attitudes toward their disabled peers. The students in the study did not perceive inclusion as a special provision; rather, they perceived inclusion as a way of instructional practice. Most of the participants in the study spoke about the multiple benefits of inclusion. They emphasized that peer integration and friendships built during classes are an essential part of their schooling. Students believed that it was part of their responsibility to assist their peers in the ways possible. This finding is in line with the literature that the personality of children with disabilities is not determined by their disability but rather by their social environment and its interaction with the child. Interactions with peers are one of the most important socio-cultural conditions for the development of children with disabilities.

Keywords: inclusion, special education, k-12 education, student voices

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Authors: Yuvraj Singh Dangi, Brajesh Kumar Tiwari, Ashok Kumar Jain, Kamta Prasad Namdeo

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The potential use of liposomes as drug carriers by i.v. injection is limited by their low stability in blood stream. Firstly, phospholipid exchange and transfer to lipoproteins, mainly HDL destabilizes and disintegrates liposomes with subsequent loss of content. To avoid the pain associated with injection and to obtain better patient compliance studies concerning various dosage forms, have been developed. Conventional liposomes (unilamellar and multilamellar) have certain drawbacks like low entrapment efficiency, stability and release of drug after single breach in external membrane, have led to the new type of liposomal systems. The challenge has been successfully met in the form of Double Liposomes (DL). DL is a recently developed type of liposome, consisting of smaller liposomes enveloped in lipid bilayers. The outer lipid layer of DL can protect inner liposomes against various enzymes, therefore DL was thought to be more effective than ordinary liposomes. This concept was also supported by in vitro release characteristics i.e. DL formation inhibited the release of drugs encapsulated in inner liposomes. DL consists of several small liposomes encapsulated in large liposomes, i.e., multivesicular vesicles (MVV), therefore, DL should be discriminated from ordinary classification of multilamellar vesicles (MLV), large unilamellar vesicles (LUV), small unilamellar vesicles (SUV). However, for these liposomes, the volume of inner phase is small and loading volume of water-soluble drugs is low. In the present study, the potential of phosphatidylethanolamine (PE) lipid anchored double liposomes (DL) to incorporate two drugs in a single system is exploited as a tool to augment the H. pylori eradication rate. Preparation of DL involves two steps, first formation of primary (inner) liposomes by thin film hydration method containing one drug, then addition of suspension of inner liposomes on thin film of lipid containing the other drug. The success of formation of DL was characterized by optical and transmission electron microscopy. Quantitation of DL-bacterial interaction was evaluated in terms of percent growth inhibition (%GI) on reference strain of H. pylori ATCC 26695. To confirm specific binding efficacy of DL to H. pylori PE surface receptor we performed an agglutination assay. Agglutination in DL treated H. pylori suspension suggested selectivity of DL towards the PE surface receptor of H. pylori. Monotherapy is generally not recommended for treatment of a H. pylori infection due to the danger of development of resistance and unacceptably low eradication rates. Therefore, combination therapy with amoxicillin trihydrate (AMOX) as anti-H. pylori agent and ranitidine bismuth citrate (RBC) as antisecretory agent were selected for the study with an expectation that this dual-drug delivery approach will exert acceptable anti-H. pylori activity.

Keywords: Helicobacter pylorI, amoxicillin trihydrate, Ranitidine Bismuth citrate, phosphatidylethanolamine, multi vesicular systems

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Authors: Kaushalendra Kumar, Abhishek Kumar, Chandra Moni, Sanjay Kumar, P. K. Singh, Ajeet Kumar

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Present study investigated the dietary inclusion of Moringa oleifera leaf meal (MOLM) on production efficiency, hemato-biochemical profile and economy of Vanaraja birds under tropical condition. Experiment was conducted for a period of 56 days on 300 Vanaraja birds randomly divided in to five different experimental groups including control of 60 birds each group replicated with 20 chicks in each replicate. T1, T2, T3, T4, and T5 were offered with 0, 5, 10, 15, and 20% Moringa oleifera leaf meal along with basal ration. All the standard managemental practices were followed during experimental period including vaccination schedule. Locally available Moringa oleifera leaves were harvested at mature stage and allowed to dry under shady and aerated conditions. Thereafter, dried leaves were milled to make a leaf meal and stored in the airtight nylon bags to avoid any possible contamination from foreign material and use for experiment. Production parameters were calculated based on the amount of feed consumed and weight gain every weeks. The body weight gain of T2 group was significantly (P < 0.05) higher side whereas T3 group was comparable with control. The feed conversion ratio for T2 group was found to be significantly (P < 0.05) lower than all other treatment groups, while none of the group was comparable with each other. At the end of the experiment blood samples were collected from birds for haematology study while serum biochemistry performed using spectrophotometer following statndard protocols. The haematological attributes were significantly (P > 0.05) not differed among the groups. However, serum biochemistry showed significant reduction (P < 0.05) of blood urea nitrogen, uric acid and creatinine level with higher level of MOLM diet, indicates better utilization of protein supplemented through MOLM. The total cholesterol and triglyceride level was declined significantly (P < 0.05) as compare to control group with increased level of MOLM in basal diet, decreasing trend of serum cholesterol noted. However, value of HDL for T3 group was highest and for T1 group was lowest but no significant difference (P < 0.05) found among the groups. It might be due to presence of β-sitosterol a bioactive compound present in MOLM which causes lowering of plasma concentration of LDL. During experiment total, LDL and VLDL level was found to be decreased significantly (P < 0.05) as compare to control group. It was observed that the production efficiency of birds significantly improved with 5% followed by 10% Moringa oleifera leaf meal among the treatment groups. However, the maximum profit per kg live weight was noted in 10 % level and least profit observed in 20% MOLM fed group. It was concluded that the dietary inclusion of MOLM improved overall performances without affecting metabolic status and effective in reducing cholesterol level reflects healthy chicken production for human consumption.

Keywords: hemato biochemistry, Moringa oleifera leaf meal, performance, Vanaraja birds

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Authors: Neelam Taneja, Abhishek Mewara, Ajay Kumar

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Multidrug resistant shigellae have emerged as a therapeutic challenge in India. At our 2000 bed tertiary care referral centre in Chandigarh, North India, which caters to a large population of 7 neighboring states, antibiotic resistance in Shigella is being constantly monitored. Shigellae are isolated from 3 to 5% of all stool samples. In 1990 nalidixic acid was the drug of choice as 82%, and 63% of shigellae were resistant to ampicillin and cotrimoxazole respectively. Nalidixic acid resistance emerged in 1992 and rapidly increased from 6% during 1994-98 to 86% by the turn of 21st century. In the 1990s, the WHO recommended ciprofloxacin as the drug of choice for empiric treatment of shigellosis in view of the existing high level resistance to agents like chloramphenicol, ampicillin, cotrimoxazole and nalidixic acid. First resistance to ciprofloxacin in S. flexneri at our centre appeared in 2000 and rapidly rose to 46% in 2007 (MIC>4mg/L). In between we had an outbreak of ciprofloxacin resistant S.dysenteriae serotype 1 in 2003. Therapeutic failures with ciprofloxacin occurred with both ciprofloxacin-resistant S. dysenteriae and ciprofloxacin-resistant S. flexneri. The severity of illness was more with ciprofloxacin-resistant strains. Till 2000, elsewhere in the world ciprofloxacin resistance in S. flexneri was sporadic and uncommon, though resistance to co-trimoxazole and ampicillin was common and in some areas resistance to nalidixic acid had also emerged. Fluoroquinolones due to extensive use and misuse for many other illnesses in our region are thus no longer the preferred group of drugs for managing shigellosis in India. WHO presently recommends ceftriaxone and azithromycin as alternative drugs to fluoroquinolone-resistant shigellae, however, overreliance on this group of drugs also seems to soon become questionable considering the emerging cephalosporin-resistant shigellae. We found 15.1% of S. flexneri isolates collected over a period of 9 years (2000-2009) resistant to at least one of the third-generation cephalosporins (ceftriaxone/cefotaxime). The first isolate showing ceftriaxone resistance was obtained in 2001, and we have observed an increase in number of isolates resistant to third generation cephalosporins in S. flexneri 2005 onwards. This situation has now become a therapeutic challenge in our region. The MIC values for Shigella isolates revealed a worrisome rise for ceftriaxone (MIC90:12 mg/L) and cefepime (MIC90:8 mg/L). MIC values for S. dysenteriae remained below 1 mg/L for ceftriaxone, however for cefepime, the MIC90 has raised to 4 mg/L. These infections caused by ceftriaxone-resistant S. flexneri isolates were successfully treated by azithromycin at our center. Most worrisome development in the present has been the emergence of DSA(Decreased susceptibility to azithromycin) which surfaced in 2001 and has increased from 4.3% till 2011 to 34% thereafter. We suspect plasmid-mediated resistance as we detected qnrS1-positive Shigella for the first time from the Indian subcontinent in 2 strains from 2010, indicating a relatively new appearance of this PMQR determinant among Shigella in India. This calls for a continuous and strong surveillance of antibiotic resistance across the country. The prevention of shigellosis by developing cost-effective vaccines is desirable as it will substantially reduce the morbidity associated with diarrhoea in the country

Keywords: Shigella, antimicrobial, resistance, India

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Authors: Suneet Jagdev, Hrishabh Amrodia, Siddharth Menon, Abhishek Singh, Mansi Shivhare

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Delhi, the National Capital, has undergone a surge in development rate, consequently engendering an unprecedented increase in population. Over the years the city has transformed into a car-centric infrastructure with high-speed corridors, flyovers and fast lanes. A considerable section of the population is hankering to rehabilitate to the good old cycling days, in order to contribute towards a green environment as well as to maintain their physical well-being. Furthermore, an extant section of Delhi’s population relies on cycles as their primary means of commuting in the city. Delhi has the highest number of cyclists and second highest number of pedestrians in the country. However, the tumultuous problems of unregulated traffic, inadequate space on roads, adverse weather conditions stifle them to opt for cycling. Lately, the city has been facing a conglomeration of problems such as haphazard traffic movement, clogged roads, congestion, pollution, accidents, safety issues, etc. In 1957, Delhi’s cyclists accounted for 36 per cent of trips which dropped down to a mere 4 per cent in 2008. The declining rate is due to unsafe roads and lack of proper cycle lanes. Now as the 10 percent of the city has cycle tracks. There is also a lack of public recreational activities in the city. These conundrums incite the need of a covered elevated cycling bridge track to facilitate the safe and smooth cycle commutation in the city which would also serve the purpose of an alternate urban public space over the cycle bridge reducing the cost as well as the space requirement for the same, developing a user–friendly transportation and public interaction system for urban areas in the city. Based on the archival research methodologies, the following research draws information and extracts records from the data accounts of the Delhi Metro Rail Corporation Ltd. as well as the Centre for Science and Environment, India. This research will predominantly focus on developing a prototype design for high speed elevated bicycle lanes based on different road typologies, which can be replicated with minor variations in similar situations, all across the major cities of our country including the proposed smart cities. Furthermore, how these cycling lanes could be utilized for the place making process accommodating cycle parking and renting spaces, public recreational spaces, food courts as well as convenient shopping facilities with appropriate optimization. How to preserve and increase the share of smooth and safe cycling commute cycling for the routine transportation of the urban community of the polluted capital which has been on a steady decline over the past few decades.

Keywords: bicycle track, prototype, road safety, urban spaces

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Authors: Anwar Beg, Sireetorn Kuharat, Rashid Mehmood, Rabil Tabassum, Meisam Babaie

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Nano-polymeric solar paints and sol-gels have emerged as a major new development in solar cell/collector coatings offering significant improvements in durability, anti-corrosion and thermal efficiency. They also exhibit substantial viscosity variation with temperature which can be exploited in solar collector designs. Modern manufacturing processes for such nano-rheological materials frequently employ stagnation flow dynamics under high temperature which invokes radiative heat transfer. Motivated by elaborating in further detail the nanoscale heat, mass and momentum characteristics of such sol gels, the present article presents a mathematical and computational study of the steady, two-dimensional, non-aligned thermo-fluid boundary layer transport of copper metal-doped water-based nano-polymeric sol gels under radiative heat flux. To simulate real nano-polymer boundary interface dynamics, thermal slip is analysed at the wall. A temperature-dependent viscosity is also considered. The Tiwari-Das nanofluid model is deployed which features a volume fraction for the nanoparticle concentration. This approach also features a Maxwell-Garnet model for the nanofluid thermal conductivity. The conservation equations for mass, normal and tangential momentum and energy (heat) are normalized via appropriate transformations to generate a multi-degree, ordinary differential, non-linear, coupled boundary value problem. Numerical solutions are obtained via the stable, efficient Runge-Kutta-Fehlberg scheme with shooting quadrature in MATLAB symbolic software. Validation of solutions is achieved with a Variational Iterative Method (VIM) utilizing Langrangian multipliers. The impact of key emerging dimensionless parameters i.e. obliqueness parameter, radiation-conduction Rosseland number (Rd), thermal slip parameter (α), viscosity parameter (m), nanoparticles volume fraction (ϕ) on non-dimensional normal and tangential velocity components, temperature, wall shear stress, local heat flux and streamline distributions is visualized graphically. Shear stress and temperature are boosted with increasing radiative effect whereas local heat flux is reduced. Increasing wall thermal slip parameter depletes temperatures. With greater volume fraction of copper nanoparticles temperature and thermal boundary layer thickness is elevated. Streamlines are found to be skewed markedly towards the left with positive obliqueness parameter.

Keywords: non-orthogonal stagnation-point heat transfer, solar nano-polymer coating, MATLAB numerical quadrature, Variational Iterative Method (VIM)

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Authors: Anubhav Kumar Dwivedi, Arshad Khan, S. N. Tripathi, Manish Joshi, Gaurav Mishra, Dinesh Nath, Naveen Tiwari, B. K. Sapra

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In a nuclear reactor accident scenario, a large number of fission products may release to the piping system of the primary heat transport. The released fission products, mostly in the form of the aerosol, get deposited on the inner surface of the piping system mainly due to gravitational settling and thermophoretic deposition. The removal processes in the complex piping system are controlled to a large extent by the thermal-hydraulic conditions like temperature, pressure, and flow rates. These parameters generally vary with time and therefore must be carefully monitored to predict the aerosol behavior in the piping system. The removal process of aerosol depends on the size of particles that determines how many particles get deposit or travel across the bends and reach to the other end of the piping system. The released aerosol gets deposited onto the inner surface of the piping system by various mechanisms like gravitational settling, Brownian diffusion, thermophoretic deposition, and by other deposition mechanisms. To quantify the correct estimate of deposition, the identification and understanding of the aforementioned deposition mechanisms are of great importance. These mechanisms are significantly affected by different flow and thermodynamic conditions. Thermophoresis also plays a significant role in particle deposition. In the present study, a series of experiments were performed in the piping system of the National Aerosol Test Facility (NATF), BARC using metal aerosols (zinc) in dry environments to study the spatial distribution of particles mass and number concentration, and their depletion due to various removal mechanisms in the piping system. The experiments were performed at two different carrier gas flow rates. The commercial CFD software FLUENT is used to determine the distribution of temperature, velocity, pressure, and turbulence quantities in the piping system. In addition to the in-built models for turbulence, heat transfer and flow in the commercial CFD code (FLUENT), a new sub-model PBM (population balance model) is used to describe the coagulation process and to compute the number concentration along with the size distribution at different sections of the piping. In the sub-model coagulation kernels are incorporated through user-defined function (UDF). The experimental results are compared with the CFD modeled results. It is found that most of the Zn particles (more than 35 %) deposit near the inlet of the plenum chamber and a low deposition is obtained in piping sections. The MMAD decreases along the length of the test assembly, which shows that large particles get deposited or removed in the course of flow, and only fine particles travel to the end of the piping system. The effect of a bend is also observed, and it is found that the relative loss in mass concentration at bends is more in case of a high flow rate. The simulation results show that the thermophoresis and depositional effects are more dominating for the small and larger sizes as compared to the intermediate particles size. Both SEM and XRD analysis of the collected samples show the samples are highly agglomerated non-spherical and composed mainly of ZnO. The coupled model framed in this work could be used as an important tool for predicting size distribution and concentration of some other aerosol released during a reactor accident scenario.

Keywords: aerosol, CFD, deposition, coagulation

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Authors: Sireetorn Kuharat, Anwar Beg

Abstract:

Motivation- Solar energy constitutes the most promising renewable energy source on earth. Nanofluids are a very successful family of engineered fluids, which contain well-dispersed nanoparticles suspended in a stable base fluid. The presence of metallic nanoparticles (e.g. gold, silver, copper, aluminum etc) significantly improves the thermo-physical properties of the host fluid and generally results in a considerable boost in thermal conductivity, density, and viscosity of nanofluid compared with the original base (host) fluid. This modification in fundamental thermal properties has profound implications in influencing the convective heat transfer process in solar collectors. The potential for improving solar collector direct absorber efficiency is immense and to gain a deeper insight into the impact of different metallic nanoparticles on efficiency and temperature enhancement, in the present work, we describe recent computational fluid dynamics simulations of an annular solar collector system. The present work studies several different metallic nano-particles and compares their performance. Methodologies- A numerical study of convective heat transfer in an annular pipe solar collector system is conducted. The inner tube contains pure water and the annular region contains nanofluid. Three-dimensional steady-state incompressible laminar flow comprising water- (and other) based nanofluid containing a variety of metallic nanoparticles (copper oxide, aluminum oxide, and titanium oxide nanoparticles) is examined. The Tiwari-Das model is deployed for which thermal conductivity, specific heat capacity and viscosity of the nanofluid suspensions is evaluated as a function of solid nano-particle volume fraction. Radiative heat transfer is also incorporated using the ANSYS solar flux and Rosseland radiative models. The ANSYS FLUENT finite volume code (version 18.1) is employed to simulate the thermo-fluid characteristics via the SIMPLE algorithm. Mesh-independence tests are conducted. Validation of the simulations is also performed with a computational Harlow-Welch MAC (Marker and Cell) finite difference method and excellent correlation achieved. The influence of volume fraction on temperature, velocity, pressure contours is computed and visualized. Main findings- The best overall performance is achieved with copper oxide nanoparticles. Thermal enhancement is generally maximized when water is utilized as the base fluid, although in certain cases ethylene glycol also performs very efficiently. Increasing nanoparticle solid volume fraction elevates temperatures although the effects are less prominent in aluminum and titanium oxide nanofluids. Significant improvement in temperature distributions is achieved with copper oxide nanofluid and this is attributed to the superior thermal conductivity of copper compared to other metallic nano-particles studied. Important fluid dynamic characteristics are also visualized including circulation and temperature shoots near the upper region of the annulus. Radiative flux is observed to enhance temperatures significantly via energization of the nanofluid although again the best elevation in performance is attained consistently with copper oxide. Conclusions-The current study generalizes previous investigations by considering multiple metallic nano-particles and furthermore provides a good benchmark against which to calibrate experimental tests on a new solar collector configuration currently being designed at Salford University. Important insights into the thermal conductivity and viscosity with metallic nano-particles is also provided in detail. The analysis is also extendable to other metallic nano-particles including gold and zinc.

Keywords: heat transfer, annular nanofluid solar collector, ANSYS FLUENT, metallic nanoparticles

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