Alamgir Hossain

The fast pace of the development of quantum engineering requires extremely stable conditions to preserve qubit coherence. The principle that requires superconducting processors is that they need very low temperatures to operate, which leads to the challenges of a sophisticated cryogenic system being a significant foundation of viable quantum hardware infrastructure. Even without it, controlling heat dissipation at the milli-Kelvin scale has been a daunting problem. Extant cooling designs often have thermal leakage problems and inefficient structural layouts, which create decoherence, and limit the physical scaling of quantum control systems. The purpose of this research is to design the thermal capacity of cryogenic systems by using an innovative approach of computational modeling. The main goal is to design a scalable 3D CAD-based system that generates the minimal thermal gradients and the highest cooling efficiency of the dense qubit arrays. Computational Fluid Dynamics (CFD) and thermo-mechanical analysis were applied in the study to undertake simulations of heat transfer in a model of a multi-stage dilution refrigerator. A computer-aided design, based on the use of the best 3D CAD tool, allowed researchers to design an ideal cryogenic housing and test the thermal isolating capacity of chosen composite materials in conditions of low temperature (ultra-low temperatures). Computational simulations enabled a reduction in parasitic heat load at a 4-Kelvin stage to be reduced by 34 % compared to baseline configurations. In addition, the CAD geometry that was optimized gave a very homogeneous temperature distribution, decreasing thermal variance by 2.1 milli-Kelvins, and conveniently allowing a 50 % control wiring density increase. Combining accurate computational thermal modeling with structural CAD design offers a sound route towards the elimination of cryogenic bottlenecks. This modular architectural strategy has had a useful impact on improving the qubit stability and is also successful in accelerating the creation of practical quantum systems.

In recent years, there has been a significant increase in the demand for renewable energy technologies worldwide. This surge is largely driven by growing concerns about climate change, decreasing fossil fuel reserves, and the desire for sustainable economic development. One promising renewable technology is biomass gasification, which offers a practical and scalable solution to global energy challenges. The present study numerically investigates biomass gasification in a downdraft gasifier under both air-fired and oxy-fired conditions. The present study numerically investigates air-fired and oxy-fired biomass gasification in a downdraft gasifier using various locally available biomass feedstocks with distinct physicochemical characteristics. The study provides insights into the effects of gasifying atmosphere and feedstock characteristics on reactor performance, temperature distribution, and syngas quality, thereby supporting the optimization of biomass gasification for sustainable energy production. The results indicated that oxy-fired gasification significantly outperforms air-fired operations, with an increase in hydrogen and carbon monoxide concentrations of approximately 25-30%. Among the feedstocks analyzed, sawdust exhibited the most favorable thermal profile under oxy-fired conditions, reaching a peak temperature of 2340 K and producing the highest hydrogen yield at 30.33%, attributed to its high volatile content. In contrast, rice straw and corn straw were found to have lower reactivity indexes. The study will contribute to the knowledge on improving the thermochemical conversion processes of biomass for maximizing both the yield and quality of the synthesized gas.

Manufacturing and municipal waste are soaring at an unprecedented rate posing an environmental threat to the global industrial sector. Conventional forms of linear disposal, landfills and incineration are neither sustainable environmentally nor economically. Even though sustainability is a pressing need, there are still major gaps in infrastructure and financial constraints. Moreover, there is still a severe gap in the comprehensive implementation of global programs on zero-waste, as the available literature does not have systematic systems to coordinate technological innovations and the over-corporate plans. The aim of the research is to explore the way in which sustainable waste management strategies can be effectively embedded in manufacturing processes to have zero-waste target and to determine the multi-level compatibility of these activities with long-term corporate strategies. Mixed methods, sequential exploratory methods, were used. The study organized information around the world with the help of a systematic literature review, studied various industrial case studies to practically prove the validity of economic and regulatory obstacles, and applied semi-structured expert interviews. Results indicated that current systems were not congruent with the principles of zero-waste, with 37% of all waste in the world kept in landfills, and operational costs of waste management reaching over 100 dollars per ton in high-income countries. Nevertheless, these approaches of incorporating the 3R concept, circular economies, and waste-to-energy indicated that there had been a deep potential of reducing the estimated 3.40 billion tons of global waste by the year 2050. This research ends up developing a holistic strategic integration framework. With the following customized suggestions in mind, manufacturing businesses will be able to sail through systemic challenges easily, diminish their impact on the environment by far, and become the chief drivers of a transition to an environmentally friendly and airtight, zero-waste future.

Exploring alternative fuels for internal combustion engines is now receiving much more attention to enhance the performance and reduce the pollutants from the engine. From this point of view, the blended fuels of pyrolytic plastic oil (PPO), diesel, and alumina (Al2O3) nanoparticles have been utilized in this study to investigate the effects of nanoparticles on Petter diesel engine performance and emission properties. During the blending of fuels through a magnetic stirrer and homogenizer, the ratio of PPO and diesel was varied in volume percentage at a step of 15% increment of PPO with 150 ppm of nanoparticles. From the experimental results, it has been observed that the blended fuel of PPO60D40A150 at 40N loading situation, exhibited the highest BTE of 23.90% as well as an increased BTE is obtained up to 2.65% compared to pure diesel at 21N loading condition. On the other hand, a reduction of BSFC and CO emission at 21N load, and NO emission at 40N loads has been observed of 16.07%, 39.38% and 62.04%, respectively. Among all the blended fuels, PPO60D40A150 has demonstrated an outstanding performance for BTE, BSFC, and NO emissions, while PPO45D55A150 has shown an impressive reduction of CO emissions. Overall, this study with different numerical values provides evidence that the addition of alumina (Al2O3) nanoparticles in the diesel engine fuels can remarkably enhance the performance and improve the emission properties of diesel engines.

Energy demand is rising over time in both developing and developed countries. Therefore, finding new sources of energy is a prime concern now. For this effort, this paper presents the pyrolysis of onion (Allium cepa) shells in a reactor with a fixed bed for generating alternative liquid fuel. This paper also compares alternative fuel characteristics, including higher heating value, viscosity, density, pour point, and flash point, with conventional petroleum fuels at optimal process conditions. The work adopted pyrolysis to produce liquid fuel at a temperature range of 400–550 °C and utilized LPG to provide a heat source. The liquid product (fuel oil) was collected, and non-condensable gas was flared. The liquid product was tested for various properties, and the results of the analyses show that alternative fuel has a higher heating value of 12.227 MJ/kg, density of 800 kg/m³, viscosity of 4.3 cP at 30 °C, pour point below −6.2 °C, and flash point around 137 °C, with a variation due to the volatile matters. To obtain favorable conditions for pyrolysis, some parameters, including bed temperature, sample quantity, average particle size, and operating time, were varied and analyzed. The physio-chemical properties made the alternative fuels isolated from conventional petroleum fuels due to the variation in distillation temperature. This work shows that the fuel oil generated from the pyrolysis of onion shells could be considered an alternative source of fuel.

This paper presents the design, fabrication, and performance test of a magnetic bearing employing no active components. In this study, the magnetic bearing was fabricated using a magnetic edge effect. Four large and three small hollow Neodymium (Nd) magnets were used of the same thickness, same internal diameter but different outer diameters. Small magnets were rigidly attached in the rotor and large magnets were fixed in the casing. In magnetic edge effects, a rotor along with small magnets was suspended inside the casing. Using stroboscope, rpm of the rotors were measured at no load, 0.5 N, 1.0 N, 1.5 N conditions for a different number of magnetic bearings in series, and the corresponding torque was calculated. After that, all the data were compared to the ball bearing set up in the same rotor. This paper shows that the speed of the magnetic bearing was doubled than the ball bearing with the same loading conditions. Required torque was 1.5 times greater in the case of ball bearing when compared to the magnetic bearing. The developed system is capable of suspending a rotor at a stable steady-state position. This suspension is accomplished by the edge effect of Nd round hollow magnets.