Recent Submissions

  • Simulation of Nitride Semiconductor MOVPE

    Ohkawa, Kazuhiro (Wiley, 2020-12-31) [Book Chapter]
    This article seeks to help readers understand the MOVPE growth of nitride semiconductors as a part of science. MOVPE is the abbreviation for metalorganic vapor-phase epitaxy. Therefore, the precursors used are metalorganic gases and ammonia. The precursors decompose or react with others in the gas phase. The obtained reactive molecules form semiconductor layers on substrates. Those growth reaction pathways and the polymer formation will be discussed numerically for GaN, InN, InGaN, AlN, and AlGaN in this article. For those materials, the numerical analyses of growth rate and alloy composition exhibited the qualitative and quantitative agreements with experiments. The reader can see the growth mechanism, and experts will understand the current MOVPE conditions of nitride semiconductors.
  • Heterojunction oxide thin-film transistors

    Faber, Hendrik; Yarali, Emre; Yengel, Emre; Anthopoulos, Thomas D. (IOP Publishing, 2020-12) [Book Chapter]
    Metal oxide (MO) semiconductors are an important class of materials for a large range of (opto)electronic applications, including as active channel material in thinfilm transistors (TFTs) for display technologies. Research effort in this field focuses on the improvement of device characteristics, with one of the main figures of merit being the electron mobility, as well as the stability against bias stress. While TFTs with a single layer MO as the channel material are limited by the inherent bulk properties of that MO, using heterojunctions (HJs) of bilayer or multilayer stacks instead offers ways to overcome those limitations. For example, interface effects such as the formation of a two-dimensional electron gas, can enhance the mobility beyond that of the single material components of the HJ. On the other hand, the combination of two layers with distinct functionalities (e.g. high mobility of material 1 with high stability and low off-currents for material 2) gives rise to well-balanced overall device characteristics that would not be achievable with either MO by itself. This chapter gives an overview of the materials, mechanisms and improvements involved with heterojunction metal oxide TFTs
  • Future of Air Conditioning

    Kian Jon, Chua; Islam, Md Raisul; Ng, Kim Choon; Shahzad, Muhammad Wakil (Springer Singapore, 2020-10-22) [Book Chapter]
    Air conditioning is essential for maintaining thermal comfort in indoor environments, particularly for buildings located in the tropics where the weather is both hot and humid. Today, air conditioning, comprising cooling and dehumidification, has become a necessity in commercial and residential buildings and even in many industrial processes. In tropical climates, the energy consumed due to heating, ventilation and air-conditioning (HVAC) alone can exceed 50% of the total energy consumption of a building. This significant figure is primarily due to the heavy-duty placed on cooling systems to remove both sensible and latent heat loads. Therefore, there is tremendous potential to improve the overall efficiency of air-conditioning systems for building applications. One of the simplest and neatest ways to reduce energy consumption for air conditioning is to decouple the sensible and latent loads imposed on cooling systems. When a separate technology is solely able to dehumidify the supply air, the cooling load imposed on the cooling system can be markedly reduced. Accordingly, the energy efficiency for cooling is promoted. This review chapter provides a key update on recent developments in air-conditioning systems, particularly innovative technologies in cooling and dehumidification. Key technologies related to sustainable cooling include absorption/adsorption cooling and dew-point evaporative cooling. Technologies connected with dehumidification involve new generations of solid-based desiccant dehumidifiers, liquid-based desiccants and novel membranes that are able to sieve out water vapour when a transmembrane pressure is provided.
  • Liquid Desiccant Air-Conditioning Systems

    Kian Jon, Chua; Islam, Md Raisul; Ng, Kim Choon; Shahzad, Muhammad Wakil (Springer Singapore, 2020-10-22) [Book Chapter]
    The liquid desiccant air-conditioning system has been identified as a promising technology that has the potential of decoupling and preciously controlling the latent and sensible cooling loads of air-conditioning spaces. The issues of moulds and bacteria growth on the wet surface of chilled water coils of conventional air handling units can be resolved by employing liquid desiccant systems, where moisture is absorbed by antibacterial desiccant solutions instead of condensing at low temperature. Considerable progress has been made by researchers to enhance the dehumidification and cooling performances of liquid desiccant systems, which are coherently presented in this chapter. The thermophysical properties of several liquid desiccants have been evaluated and the opportunities for improving the desired properties by mixing different desiccant materials are explored. Techniques for improving the wettability and flow characteristics of the packing materials are also discussed. In addition, several theoretical models and solution techniques to study heat and mass transfer enhancement opportunities are systematically discussed and compared in this chapter. The potential of a hybrid liquid desiccant system incorporating either a conventional vapour compression system ora vapour absorption chiller is also documented. Finally, some challenges and future research directions are identified and discussed.
  • Present State of Cooling, Energy Consumption and Sustainability

    Kian Jon, Chua; Islam, Md Raisul; Ng, Kim Choon; Shahzad, Muhammad Wakil (Springer Singapore, 2020-10-22) [Book Chapter]
    The rise in temperature is an on-going issue due to global warming. The air-conditioning demand is expected to be triple by 2050 to provide comfortable environment at offices and residential buildings. In most of the deserted countries, the annual cooling degree days are over 4000 due to harsh weather conditions. Presently, over 6 billion air-conditioning units are installed globally including refrigeration systems and it is expected to increase exponentially in next decades. This inexorable growth in air-conditioners capacity not only increasing the energy demand due to low performance of conventional systems but also contributing a huge amount of CO2 and greenhouse gas emissions. The levelling-off the efficiency of conventional chillers at 0.85 ± 0.03 kW/Rton coupled with chemical-based refrigerants is the major limitation of conventional mechanical chillers covering 90% world air-conditioning market. To continue sustainable development, out-of-box solutions are required. The future air-conditioning systems must achieve the performance level of 0.60 ± 0.03 kW/Rton to fulfil the cooling demand in sustainable manner. Decoupling of dehumidification from cooling is one of the solutions to overcome the conventional system limitation to achieve satiable cooling goals.
  • Dissipative Losses in Cooling Cycles

    Kian Jon, Chua; Islam, Md Raisul; Ng, Kim Choon; Shahzad, Muhammad Wakil (Springer Singapore, 2020-10-22) [Book Chapter]
    To improve the energy efficiencies of cooling cycles, it is important to identify the key sources of internal dissipative losses, thus pinpointing the major inefficient components that require optimization. This chapter conducts a second-law analysis on different cooling systems, including a mechanical vapour compression chiller, an absorption chiller, an adsorption chiller, and an indirect evaporative cooler. Based on thermodynamic states of these systems, the entropy generation rates of each component are calculated which revealed that the compressor, the regenerative heat exchangers and the reactor beds account for the most dissipative losses in mechanical chillers, absorption and adsorption chillers. The exergy efficiency of mechanical chillers can be improved by promoting the heat transfer in the evaporators and the condensers. The system-level entropy generation rates are normalized with respect to the cooling capacities to allow a direct comparison of different systems. The indirect evaporative cooler is found to perform most efficiently among the compared cooling cycles, while the adsorption chiller incurs the most internal dissipations due to poor heat transfer in its porous adsorbents.
  • Adsorbent-Coated Heat and Mass Exchanger

    Kian Jon, Chua; Islam, Md Raisul; Ng, Kim Choon; Shahzad, Muhammad Wakil (Springer Singapore, 2020-10-22) [Book Chapter]
    This chapter specifically focuses on the development of the adsorbent coated heat and mass exchanger as a promising energy-efficient alternative for the dehumidification and cooling of air using the low-grade waste heat. A comprehensive and compact overview is conducted on the adsorption and desorption characteristics of different high-performance pure and composite adsorbents. The moisture adsorption performance of commonly used adsorbents, such as silica gel, activated carbon, Y-type zeolite, AQSOA-Z01, AQSOA-Z02, and AQSOA-Z03 are compared. Different techniques to facilitate durable and uniform coating of adsorbents on the heat exchanger surfaces are presented. The relative advantages and challenges of the adsorbent-coated heat and mass exchanger over the fixed-bed and the rotary wheel dehumidifiers are coherently analysed. Finally, the influences of key design and operating variables on the performance of dehumidification and cooling of air using standalone as well as various hybrid heat and mass exchanger systems are systematically documented and discussed.
  • Membrane Air Dehumidification

    Kian Jon, Chua; Islam, Md Raisul; Ng, Kim Choon; Shahzad, Muhammad Wakil (Springer Singapore, 2020-10-22) [Book Chapter]
    Membrane-based air dehumidification (MAD), a recently emerged air dehumidification technology, separates the moisture from the humid air by using a selective membrane. MAD is carried out by permitting only vapour molecules to transfer from one side of the membrane at a high concentration to the other side at a low concentration. The MAD process has superior performance translating to favourable energy and economic benefits than other traditional dehumidification technologies. This chapter comprehensively reviews the literature on MAD including membrane characteristics, membrane configuration, membrane-related mass transport mechanism, and system design and operation as well as the mass transfer modelling. State-of–the-art developments in MAD are presented and finally recommendations on future research directions are provided. This chapter provides a comprehensive discussion of the MAD technology including membrane materials, thermophysical characterization, membrane forms and modules, system configurations, and mass transport modelling.
  • Dew-Point Evaporative Cooling Systems

    Kian Jon, Chua; Islam, Md Raisul; Ng, Kim Choon; Shahzad, Muhammad Wakil (Springer Singapore, 2020-10-22) [Book Chapter]
    Maisotsenko cycle (M-cycle) is a promising air-cooling technique that can reduce the temperature of airflow to approaching dew-point condition, which was not possible either with direct contact techniques or indirect evaporative methods. M-cycle systems have been employed previously on gas turbines, air-conditioning systems, cooling towers, electronic cooling, etc. Due to the wide application of air conditioning systems, this chapter focuses on the application of M-cycle specifically for air conditioning purpose. Researchers have evaluated the M-cycle cooling characteristics via different methods including analytical solutions, numerical simulations, statistical design methods, and experimental techniques. The salient aspects of these methods are systematically discussed and compared in this chapter. In addition, the current status of the applying the dew-point evaporative cooling systems to meet industrial needs is summarized and some of the future research directions are also identified.
  • Bayes Meets Tikhonov: Understanding Uncertainty Within Gaussian Framework for Seismic Inversion

    Izzatullah, Muhammad; Peter, Daniel; Kabanikhin, Sergey; Shishlenin, Maxim (Springer Singapore, 2020-10-22) [Book Chapter]
    In this chapter, we demonstrate the sound connection between the Bayesian approach and the Tikhonov regularisation within Gaussian framework. We provide a thorough uncertainty analysis to answer the following two fundamental questions: (1) How well is the estimate determined by a posteriori PDF, i.e. by the combination of observed data and a priori information? (2) What are the respective contributions of observed data and a priori information? To support the proposed methodology, we demonstrate it through numerical applications in seismic inversions.
  • Efficacy Comparison for Cooling Cycles

    Kian Jon, Chua; Islam, Md Raisul; Ng, Kim Choon; Shahzad, Muhammad Wakil (Springer Singapore, 2020-10-22) [Book Chapter]
    Conventionally, mechanical vapour compression chillers are considered to be the most appropriate solutions for commercial and industrial air-conditioning applications. There are many categories of conventional chillers based on their cooling mechanism and operational arrangements. To evaluate their performance, numerous international and national test standards have been established. The most common efficiency parameter is coefficient of performance and it is accepted globally. On the other hand, the indirect evaporative cooler (IEC) has emerged to be an alternative air-conditioning solution but there is currently no international standard to evaluate its performance. A mathematical model is developed to evaluate the performance of both conventional chillers and indirect evaporative coolers. It showed that the indirect evaporative cooler performance is much higher (COP = 21.52 cooling only) when compared with the conventional chiller (COP = 3.26). In addition, the water consumption of the indirect evaporative cooler is also lower compared with conventional chillers. The indirect evaporative cooler can be one of the best solutions for future cooling needs. Presently, there are established performance measurement parameters for conventional chillers such as EER, SEER, COP and SCOP together with test standards for performance calculations. Unfortunately, there is no international standard available for IEC systems even though there are some regional standards employed to evaluate the performance of IEC systems. In this chapter, the details on available performance parameters are provided including all international standards. In addition, a sample calculation is provided to enable the performances of conventional chillers and IEC to be evaluated for commercial references.
  • Thermo-Economic Analysis for Cooling Cycles

    Kian Jon, Chua; Islam, Md Raisul; Ng, Kim Choon; Shahzad, Muhammad Wakil (Springer Singapore, 2020-10-22) [Book Chapter]
    The levelized cost of cooling accounts for the costs of cooling systems throughout their life cycle and is an effective measurement of the economic viability of cooling cycles. This chapter presents a life-cycle economic analysis of different cooling cycles. Economic and thermodynamic performance data are firstly collected from open literature. The cost of cooling over the plant lifetime is then calculated considering different energy sources. Results revealed that the mechanical chiller and the indirect evaporative cooler are the most cost-effective under the regular scenario, while heat-driven processes like absorption and adsorption cooling cycles are expensive due to high thermal energy costs. Costs of thermally driven cycles can be reduced if low-cost thermal energy sources are available, and under such situations, the absorption chiller can become a viable option. The cooling costs are also strongly impacted by interest rate, annual operation hour, and energy efficiency. Therefore, optimal design, selection, and energy efficiency are key to sustaining low capital and operating costs. The derived results offer a robust and convenient basis for selecting cooling systems in real applications.
  • Natural deep eutectic solvents in plants and plant cells: In vitro evidence for their possible functions

    Dai, Yuntao; Varypataki, Eleni Maria; Golovina, Elena A.; Jiskoot, Wim; Witkamp, Geert Jan; Choi, Young Hae; Verpoorte, Robert (Elsevier, 2020-10-21) [Book Chapter]
    The components of natural deep eutectic solvents (NADES) are abundant in plants. This led to our hypothesis that NADES may play an important role in solubilizing, storing, and transporting poorly water-soluble metabolites in living cells, adjusting the water content of plants, and protecting cells when in harsh conditions. In order to test these hypothetical roles, diverse plant materials were analyzed, including leaves, petals, plant secretions and seeds. Comparatively high amounts of ingredients of NADES are observed in those organs. In particular, resurrection plants in dry state contain a higher amount of NADES components than fresh ones, and the level of NADES components is specifically higher in the outside layer (aleurone and seed cover) of barley, than in the inside (endosperm and embryo) layer. A high accumulation of sugars, sugar alcohols, amines, amino acids, and organic acids dominate plant secretions such as sap and nectar, often in typical molar ratios of NADES. This strongly supports the hypothesis of the existence of NADES in plants. For the roles, experimentally, NADES and water were mixed resulting in liquids with different compositions and properties. In the case of plants, NADES and water co-exist in the cells and may form ideal solvents for metabolites of diverse polarities and macromolecules. Some NADES are hygroscopic, providing evidence for possible water level controlling effects of NADES in plants. Most importantly, NADES may accumulate around the lipid bilayers, form intermolecular bonds with the polar heads of lipids, and stabilize the membrane, as revealed in experiments with liposomes. This study gives in vitro evidence for the different roles NADES may play in living organisms, and opens perspectives for further exploring the existence and functions of NADES in plants cells. The omics allows now to identify all molecules in an organism or even in a cell. The challenge for future research will be to understand how there molecules interact in the dynamic cellular processes and their compartmentation on a nanoscale. In other words the challenge is to unravel the molecular interactions in the three dimensions of space and the one of time, which will require a true multidisciplinary collaboration.
  • Visual Abstraction

    Viola, Ivan; Chen, Min; Isenberg, Tobias (Springer Nature, 2020-08-12) [Book Chapter]
    In this chapter, we revisit the concept of abstraction as it is used in visualization and put it on a solid formal footing. While the term “abstraction” is utilized in many scientific disciplines, arts, as well as everyday life, visualization inherits the notion of data abstraction or class abstraction from computer science, topological abstraction from mathematics, and visual abstraction from arts. All these notions have a lot in common, yet there is a major discrepancy in the terminology and basic understanding about visual abstraction in the context of visualization. We thus root the notion of abstraction in the philosophy of science, clarify the basic terminology, and provide crisp definitions of visual abstraction as a process. Furthermore, we clarify how it relates to similar terms often used interchangeably in the field of visualization. Visual abstraction is characterized by a conceptual space where this process exists, by the purpose it should serve, and by the perceptual and cognitive qualities of the beholder. These characteristics can be used to control the process of visual abstraction to produce effective and informative visual representations.
  • The Prager–Synge theorem in reconstruction based a posteriori error estimation

    Bertrand, Fleurianne; Boffi, Daniele (American Mathematical Society, 2020-07-30) [Book Chapter]
    In this paper we review the hypercircle method of Prager and Synge. This theory inspired several studies and induced an active research in the area of a posteriori error analysis. In particular, we review the Braess–Schoberl error estimator in the context of the Poisson problem. We discuss adaptive finite element schemes based on two variants of the estimator and we prove the convergence and optimality of the resulting algorithms.
  • Cargo-delivering nanodiamonds

    Moosa, Basem; Khashab, Niveen M. (CRC Press, 2020-07-10) [Book Chapter]
    More than 50 years ago, nanodiamonds (NDs) were first discovered in Union of Soviet Socialist Republic (USSR), where they were produced by detonation reaction of carbon-based explosives. They remained essentially unknown to the rest of the world, for many reasons including security and the lack of industrial interests, until the end of the 1980s. A number of important discoveries in the late 1990s led to a wide interest in these nanoparticles (Figure 23.1). By then, mass production of NDs had already started in different countries (Osawa 2010).
  • Forget About Electron Micrographs: A Novel Guide for Using 3D Models for Quantitative Analysis of Dense Reconstructions

    Boges, Daniya; Agus, Marco; Magistretti, Pierre J.; Cali, Corrado (Springer US, 2020-06-30) [Book Chapter]
    With the rapid evolvement in the automation of serial micrographs, acquiring fast and reliably giga- to terabytes of data is becoming increasingly common. Optical, or physical sectioning, and subsequent imaging of biological tissue at high resolution, offers the chance to postprocess, segment, and reconstruct micro- and nanoscopical structures, and then reveal spatial arrangements previously inaccessible or hardly imaginable with simple, single section, two-dimensional images. In some cases, three-dimensional models highlighted peculiar morphologies in a way that two-dimensional representations cannot be considered representative of that particular object morphology anymore, like mitochondria for instance. Observations like these are taking scientists toward a more common use of 3D models to formulate functional hypothesis, based on morphology. Because such models are so rich in details, we developed tools allowing for performing qualitative, visual assessments, as well as quantification directly in 3D. In this chapter we will revise our working pipeline and show a step-by-step guide to analyze our dataset.
  • An Expanded Mixed Finite Element Method for Space Fractional Darcy Flow in Porous Media.

    Chen, Huangxin; Sun, Shuyu (Computational Science – ICCS 2020, Springer International Publishing, 2020-06-15) [Book Chapter]
    In this paper an expanded mixed formulation is introduced to solve the two dimensional space fractional Darcy flow in porous media. By introducing an auxiliary vector, we derive a new mixed formulation and the well-possedness of the formulation can be established. Then the locally mass-conservative expanded mixed finite element method is applied for the solution. Numerical results are shown to verify the efficiency of the proposed algorithm.
  • Computational singular perturbation method and tangential stretching rate analysis of large scale simulations of reactive flows: Feature tracking, time scale characterization, and cause/effect identification. Part 1, basic concepts

    Valorani, M.; Creta, F.; Ciottoli, P. P.; Malpica Galassi, R.; Goussis, D. A.; Najm, H. N.; Paolucci, S.; Im, Hong G.; Tingas, E. A.; Manias, D. M.; Parente, A.; Li, Z.; Grenga, T. (Springer International Publishing, 2020-05-29) [Book Chapter]
    This chapter provides a review of the basic ideas at the core of the Computational Singular Perturbation (CSP) method and the Tangential Stretching Rate (TSR) analysis. It includes a coherent summary of the theoretical foundations of these two methodologies while emphasizing theirmutual interconnections. The main theoretical findings are presented in a systematic fashion. Their virtues and limitations will be discussed with reference to auto-ignition systems, laminar and turbulent premixed flames, and non-premixed jet flames. The material presented in the chapter constitutes an effective guideline for further studies.
  • Computational singular perturbation method and tangential stretching rate analysis of large scale simulations of reactive flows: Feature tracking, time scale characterization, and cause/effect identification. Part 2, analyses of ignition systems, laminar and turbulent flames

    Valorani, M.; Creta, F.; Ciottoli, P. P.; Malpica Galassi, R.; Goussis, D. A.; Najm, H. N.; Paolucci, S.; Im, Hong G.; Tingas, E. A.; Manias, D. M.; Parente, A.; Li, Z.; Grenga, T. (Springer International Publishing, 2020-05-29) [Book Chapter]
    Chapter 3 summarized the highlights of the concepts behind the CSP method and the TSR analysis. In this chapter, we will discuss a few applications of these techniques.

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