56 research outputs found

    A Proposed Quantum Hamiltonian Encoding Framework for Time Evolution Operator Design of Potential Energy Function

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    The exploration of potential energy operators in quantum systems holds paramount significance, offering profound insights into atomic behaviour, defining interactions, and enabling precise prediction of molecular dynamics. By embracing the Born-Oppenheimer picture, we delve into the intricate quantum evolution due to potential energy, facilitating accurate modelling and simulation of atomic phenomena with improved quantum fidelity. This research delves into time evolution operation due to potential energy functions for applications spanning quantum chemistry and condensed matter physics. Challenges in practical implementation, encompassing the formidable curse of dimensionality and intricate entangled interactions, are thoughtfully examined. Drawing upon seminal works, we lay a robust foundation for comprehensive investigations into potential energy landscapes with two proposed algorithms. In one methodology, we have shown a systematic decomposition of the potential energy function into Hadamard bases with composite construction of Pauli-Z, identity and RZ gates which can construct the unitary time evolution operator corresponding to the potential energy with a very high fidelity. The other method is a trade-off between complexity and fidelity, where we propose a novel quantum framework that can reduce the gate complexity from {\Theta}(2n) to {\Theta}(nCr ) (for some r < n). The proposed quantum algorithms are capable of efficiently simulating potential energy operators. The algorithms were implemented in simulators and IBM quantum hardware to prove their efficac

    Morphology and cyclic voltammetry analysis of in situ polymerized polyaniline/graphene composites

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    Graphene (G) was synthesized from normal graphite powder via graphene oxide (GO). Graphene was also produced from finer particles of graphite subjected to ball milling to check the effect of particle size of graphene on the properties of composite. PANI/graphene composites of different compositions were prepared by in situ polymerization of aniline to polyaniline in the presence of graphene powder. Graphene, graphene oxide and PANI/graphene composites were characterized by UV, IR, TEM, and cyclic voltammetry. PANI/graphene composites exhibit higher current in cyclic voltammetry study compared to either neat PANI or neat graphene. The value of capacitance achieved for PANI/graphene composites is found to depend on the size of graphene particles, finer the particle higher is the capacitance for the composites. However, the effect of composition on CV characteristics of composite is relatively less pronounced compared to the size of graphene sheets coated with PANI

    Effect of Polymerization Conditions on Thermal and Mechanical Properties of Ethylene/1-Butene Copolymer Made with Ziegler-Natta Catalysts

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    The effect of polymerization conditions on thermal and mechanical properties of ethylene/1-butene copolymers synthesized through titanium-magnesium-supported Ziegler-Natta catalysts was studied. The increase in hydrogen pressure leads to a decrease in molecular weight (MW), storage modulus, and melting temperature. However, it yields an increase in molecular weight distribution (MWD), tan , % crystallinity, tensile modulus, yield stress, and strain at break. The effects of ethylene pressure and polymerization temperature on the copolymer MW, MWD and thermal and mechanical properties have been investigated. However, the impacts of ethylene pressure and polymerization temperature on copolymer modulus, tensile strength, % crystallinity, crystallization peak temperature, yield stress, strain at break, and yield strain are marginal. The hydrogen pressure plays a major role in controlling the copolymer properties because it acts as an efficient chain transfer agent during polymerization reaction. The MW is the key parameter that influences flow activation energy. However, the other mechanical, dynamic mechanical, and thermal properties not only depend on MW but are also influenced by other parameters

    ‘We knew a cyclone was imminent’:Hazard preparedness and disaster management efficiency nexus in coastal Bangladesh

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    "Natural hazard-prone countries in the global south adopted an anticipatory-preparedness approach in disaster risk reduction (DRR) by shifting away from the response and rehabilitation approach. It was highly associated with the policy recommendations of the United Nations Office for Disaster Risk Reduction (UNDRR) framework. Nevertheless, challenges remained in managing disaster risks due to heterogeneous efficiency among disaster managers. This research examines the institutional effectiveness of the disaster management agency in cyclone-prone areas in southwestern coastal Bangladesh through network analysis. This research also explores institutional efficiency’s impact on household preparedness in mitigating losses. We collected two distinct data sets from the local Union Disaster Management Committee (UDMC) and households in the same operational area of UDMC that were at risk of cyclonic disasters. To evaluate the effectiveness of local disaster management institutions, we conducted structured interviews with 336 representatives, spanning eight UDMCs in the cyclone-prone regions. To assess the impact of institutional performance (specifically, the UDMCs) on household disaster preparedness and loss mitigation, we collected data from 696 at-risk households. These households were located within the operational zones of the eight UDMCs, and the data was obtained using a structured questionnaire. Based on the application of social network analysis, our findings demonstrated that UDMC members were more active in the aftermath of disasters, as confirmed by three centrality measures - degree, eigenvector, and betweenness. Consequently, upon employing the Negative Binomial and Poisson regression models, we found a positive association between household engagement with UDMCs and participation in disaster preparedness training. This training appeared to enhance the knowledge and capacity of the respondents. The spill-over effects from disaster preparedness appeared to bolster the resilience of at-risk households, assist them in avoiding disaster-induced damages, and maintain consumption stability in the wake of disasters.

    Education for all realities, achievements and challenges. The story of Bangladesh

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    Bangladesh has made significant improvement in education covering the six EFA goals. Yet, challenges in education are also in the race. This paper attempts to highlight the successes and challenges in education of Bangladesh. It also conveys s sort of way forward for further realization of educational progresses as well as a broader range of post-2015 education goals. Education for All (EFA) adopted in Dakar World Education Forum 2000 is approaching its deadline in September 2015. Attention has been given worldwide to think further for achieving EFA targeting 2030. Will countries like Bangladesh be in a position to achieve the new targets with appropriate strategies, focused priorities and timelines, adequate resourcing and strong political commitment? (DIPF/Orig.)Bangladesh hat beachtliche Fortschritte gemacht, um die sechs EFA-Ziele zu erreichen. Gleichwohl bleiben viele Fragen offen. Der Aufsatz beabsichtigt, einerseits die Erfolge zu beschreiben, andererseits auch die Defizite aufzuzeigen. Ferner wird beschrieben, welche Aufgaben in Zukunft bewĂ€ltigt und welche Bildungsziele nach 2015 angestrebt werden sollen. Bildung fĂŒr alle (EFA) – wie sie in Dakar auf dem Weltbildungsforum in 2000 verabschiedet wurde – nĂ€hert sich der Deadline im September 2015. Weltweit wird das Augenmerk auf Überlegungen gerichtet, wie weiter mit Blick auf die Erreichung der EFA-Ziele bis 2030 gedacht wird. Werden LĂ€nder wie Bangladesch in der Lage sein, die neuen Ziele mit geeigneten Strategien, mit fokussierten PrioritĂ€ten und Zeitperspektiven, mit angemessener Mittelausstattung (DIPF/Orig.

    High speed motion control of CNC machince tools

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    High speed machining is a relatively new technology that has been applied to industries such as aerospace and die and mold making. By maximizing feedrates and cutting speeds of computer numerically controlled (CNC) machine tools, high levels of productivity are achieved. High speed machining requires rigid tool structures, stable spindles with high power and feed drives which can follow the desired tool trajectory. It is important to point out that both velocity and acceleration are physically constrained for any machine tool. However, the paths supplied by Computer Aided Design (CAD) systems do not take machine constraints into account. Thus, they usually provide very conservative (slow) part programs to this CNC machine, and the operator is then required to adjust the feedrates manually. This process is tedious, and attempts at providing improved preprocessors between the CAD system and the CNC tool have not been successful commercially, since there are too many unknown process parameters. As a result, realtime control techniques such as Cross Coupled Control (CCC), Zero Phase Error Tracking Control (ZPETC), or Realtime Feedrate Modulation (FM) have been studied in the literature. This thesis compares the performance of these traditional control techniques in their ability to reduce path error. It is shown that none of these algorithms are universally applicable to both corner tracking and circular interpolation, which are two of the most common challenges in high speed machining. The thesis then presents two new tracking algorithms that improve and combine the benefits of the existing algorithms. First, a new Linearized Cross Coupled Control (LCCC) algorithm is presented that is easier to implement than traditional CCC and improves the corner tracking capabilities. Then an algorithm termed Robust Tracking Control (RTC) is presented that combines LCCC with FM in order to further improve corner tracking performance and robustness towards multiple machining constraints. Experiments on a custom built x-y table show that RTC performs extremely well in both corner tracking and circular interpolation, even when multiple constraints such as current saturation and voltage saturation are present.Applied Science, Faculty ofEngineering, School of (Okanagan)Graduat

    A New Insight in Determining the Percolation Threshold of Electrical Conductivity for Extrinsically Conducting Polymer Composites through Different Sigmoidal Models

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    The electrical conductivity of extrinsically conducting polymer composite systems passes through a transition state known as percolation threshold. A discussion has been made on how different Sigmoidal models (S-models), such as Sigmoidal–Boltzmann (SB), Sigmoidal–Dose Response (SD), Sigmoidal–Hill (SH), Sigmoidal–Logistic (SL), and Sigmoidal–Logistic-1 (SL-1), can be applied to predict the percolation threshold of electrical conductivity for ethylene vinyl acetate copolymer (EVA) and acrylonitrile butadiene copolymer (NBR) conducting composite systems filled with different carbon fillers. An interesting finding that comes from these observations is that the percolation threshold for electrical conductivity determined by SB and SD models are similar, whereas, the other models give different result when estimated for a particular composite system. This similarity and discrepancy in the results of percolation threshold have been discussed by considering the strength, weakness, and limitation of the models. The percolation threshold value for the composites has also been determined using the classical percolation theory and compared with the sigmoidal models. Moreover, to check the universal applicability, these Sigmoidal models have also been tested on results from some published literature. Finally, it is revealed that, except SL-1 model, the remaining models can successfully be used to determine the percolation threshold of electrical conductivity for extrinsically conductive polymer composites

    Chemical and Electrochemical Synthesis of Polypyrrole Using Carrageenan as a Dopant: Polypyrrole/Multi-Walled Carbon Nanotube Nanocomposites

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    In this article, iota-carrageenan (IC) and kappa-carrageenan (KC) are used as dopants for the chemical and electrochemical synthesis of polypyrrole (PPy). The composites of chemically synthesized PPy with multi-walled carbon nanotubes (MWNTs) were prepared using an in situ technique. Both the dialyzed and non-dialyzed IC and KC were used as dopants for electrochemical polymerization of pyrrole. Chemically synthesized PPy and PPy/MWNTs composites were studied by ultraviolet visible (UV-vis) absorption spectra to investigate the effect of the concentration and the incorporation of MWNTs. In addition, the electrical, thermal, mechanical, and microscopic characterizations of these films were performed to examine the effect of the dopants and MWNTs on these properties, along with their surface morphology. The films of electrochemically polymerized PPy were characterized using UV-vis absorption spectra, scanning electron microscopy, and cyclic voltammetry (CV). The results were then compared with the chemical polymerized PPy

    A Strategy to Enhance the Electrode Performance of Novel Three-Dimensional PEDOT/RVC Composites by Electrochemical Deposition Method

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    In this article, three-dimensional (3D) microstuctured poly(3,4-ethylenedioxythiophene) (PEDOT)/reticulated vitreous carbon (RVC) composite electrodes with varying amount of PEDOT loadings were successfully prepared by electrochemical deposition method. The composites were characterized by Raman spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and cyclic voltammetry. Raman spectra suggest that there is a strong interaction between the RVC and backbone of PEDOT chain. It is revealed from the SEM images that the PEDOT amount, thickness, surface roughness, porosity, and globular structure on RVC electrode are increased with the increase in polymerization time. The capacitance of PEDOT/RVC electrode has increased by a factor of 2230 compared to a bare RVC electrode when polymerization is carried out for 120 min. Moreover, the capacitance of PEDOT was found to be very high compared with other PEDOT studies. The electrodes also show good cyclic stability. This substantial increase in capacitance of RVC electrode is due to the rough, highly porous, and honeycomb-like fine structure of PEDOT coating, which shows a flower-like morphology, consisting of numerous thin flakes with numbers of macropores and micropores. This interesting morphology has enhanced the performance of PEDOT because of increased electrode surface area, specific capacitance, and macroporous structure of RVC electrode

    Effect of Different Gamma Dose and Chemical Etching on Pre- and Post-Alpha-Irradiated PM-355 Polymer

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    This work is based on the effect of different gamma doses with pre- and post-alpha-irradiated PM-355 polymer (polycarbonate of allyl diglycol). The phase crystallinity and structural analysis of the reference and irradiated PM-355 polymer were analyzed using an X-ray diffraction (XRD) study. It is revealed that the irradiation and etching reduce the %crystallinity but increase the crystallite size of the PM-355 polymer. The increase in crystallite size of PM-355 polymer after irradiation is supported by the scanning electron microscopic (SEM) analysis. The etching of the samples results in an increase in its track diameter. The optical band gap energy, measured by ultraviolet-visible (UV-VIS) spectroscopy, shows a decrement trend with the increase of gamma and alpha irradiation doses, and etching for all sets of samples under investigation. The number of carbon atoms per conjugation and per cluster has increased after gamma irradiation and etching. However, the increment is more pronounced for etched samples compared to nonetched ones. This indicates that etching results in a bigger size of cluster. Photoluminescence (PL) for both cases before and after etching has a dominant peak around 430 nm before and after irradiation, and change in peak intensity after irradiation confirmed that particle bombardment induced defects and clusters in the PM-355, which serves as nonradiative centers. The polymer can be used as a detector for gamma irradiation
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