• Effect of Pre-chamber Enrichment on Lean Burn Pre-chamber Spark Ignition Combustion Concept with a Narrow-throat Geometry

  Hlaing, Ponnya; Marquez, Manuel Echeverri; Singh, Eshan; Almatrafi, Fahad; Cenker, Emre; Ben Houidi, Moez; Johansson, Bengt (The Society of Automotive Engineers, 2020-04-14) [Conference Paper]

  Pre-chamber spark ignition (PCSI) combustion is an emerging lean-burn combustion mode capable of extending the lean operation limit of an engine. The favorable characteristic of short combustion duration at the lean condition of PCSI results in high indicated efficiencies and low specific fuel consumption compared to conventional spark ignition combustion. Since the engine operation is typically lean, PCSI can significantly reduce engine-out NOx emissions while maintaining relatively short combustion duration. In this study, experiments were conducted on a heavy-duty engine at mid to low loads to study the effects of pre-chamber enrichment on globally lean combustion with methane fuel injection in both pre and main chambers. Two parametric variations were performed where, in the first study, the total fuel energy input to the engine was fixed while the intake pressure was varied, which resulted in varying the global air excess ratio. In the second, the intake pressure was fixed while the amount of fuel injection was changed to alter the global air excess ratio. At each global air excess ratio, the fuel injection to the pre-chamber was varied parametrically to assess the effect of pre-chamber enrichment on engine operating characteristics. Multi-chamber heat release analysis was performed in order to investigate the pre-chamber and main chamber heat release characteristics separately. The discharge coefficient of the pre-chamber nozzles was estimated by the model calibration using a 1-D GT Power Model. The analyzed data revealed two-stage combustion in the main chamber where the second stage is thought to be indicating auto-ignition of the main chamber charge. As the global air excess ratio became leaner, the combustion efficiency deteriorates as the emissions of HC and CO increased while NOx emission declined significantly. The resulting heat release data is presented alongside the engine-out specific emissions.
• 

  Image Embedding into Generative Adversarial Networks

  Abdal, Rameen (2020-04-14) [Thesis]
  Advisor: Wonka, Peter
  Committee members: Hadwiger, Markus; Ghanem, Bernard

  We propose an e cient algorithm to embed a given image into the latent space of StyleGAN. This embedding enables semantic image editing operations that can be applied to existing photographs. Taking the StyleGAN trained on the FFHQ dataset as an example, we show results for image morphing, style transfer, and expression transfer. Studying the results of the embedding algorithm provides valuable insights into the structure of the StyleGAN latent space. We propose a set of experiments to test what class of images can be embedded, how they are embedded, what latent space is suitable for embedding, and if the embedding is semantically meaningful.
• A Homeotic Mutation Changes Legume Nodule Ontogeny into Actinorhizal-type Ontogeny.

  Shen, Defeng; Xiao, Ting Ting; Velzen, Robin van; Kulikova, Olga; Gong, Xiaoyun; Geurts, Rene; Pawlowski, Katharina; Bisseling, Ton (The Plant cell, American Society of Plant Biologists (ASPB), 2020-04-12) [Article]

  Some plants can fix atmospheric nitrogen by hosting symbiotic diazotrophic rhizobia or Frankia bacteria in root organs, known as nodules. Such nodule symbiosis occurs in ten lineages in four taxonomic orders; Fabales, Fagales, Cucurbitales and Rosales, which collectively are known as the nitrogen-fixing clade (NFC). Based on differences in ontogeny and histology, nodules have been divided into two types: legume-type and actinorhizal-type nodules. The evolutionary relationship between these nodule types has been a long-standing enigma for molecular and evolutionary biologists. Recent phylogenomic studies on nodulating and non-nodulating species in the NFC indicated a shared evolutionary origin of the nodulation trait in all ten lineages. However, this hypothesis faces a conundrum that legume-type and actinorhizal-type nodules have been regarded as fundamentally different. Here, we analysed the actinorhizal-type nodules formed by Parasponia andersonii (Rosales) and Alnus glutinosa (Fagales), and found that their ontogeny is more similar to that of legume-type nodules (Fabales) than generally assumed. We also show that in Medicago truncatula a homeotic mutation in the co-transcriptional regulator encoding gene NODULE ROOT1 (MtNOOT1) converts a legume-type nodule into actinorhizal type. These experimental findings suggest that the two nodule types have a shared evolutionary origin.
• One-step electrosynthesized molecularly imprinted polymer on laser scribed graphene bisphenol a sensor

  Beduk, Tutku; Ait Lahcen, Abdellatif; Tashkandi, Nouran Abdulatif; Salama, Khaled N. (Sensors and Actuators B: Chemical, Elsevier BV, 2020-04-11) [Article]

  Bisphenol A (BPA) is a toxic chemical used by industries for production of containers for storage of food and beverages leading to possible health risks. In this work, we present a simple, mask-free, low-cost imprinted sensor based on laser scribed graphene (LSG) technology combined to molecularly imprinted polymers (MIPs) for BPA determination. CO2 laser was used in production of LSG electrodes with high conductivity and multilayer structure by using less laser speed/ power (2.8 cm/s /3.2 W) and low resistivity 58 Ω/square on flexible polyimide sheet leading to the high active surface area of the sensor. LSG device was functionalized with imprinted polypyrrole with a known amount of BPA as template molecule to develop the sensor. The bare LSG, LSG-MIP, LSG-NIP sensors were characterized using Raman spectroscopy, SEM, XRD, AFM. The electrochemical measurements were carried out using cyclic voltammetry and differential pulse voltammetry. Experimental conditions were optimized, including the concentration of pyrrole monomer, the number of polymerization cycles, the concentration of BPA as template and the incubation time. We evaluated the sensitivity of the LSG-MIP sensor in the concentration range between 0.05 µM and 20 µM with a limit of detection of 8 nM. The proposed sensor exhibits high selectivity towards BPA compared to its structural analogs and good reusability. The developed sensor was successfully applied for the detection of BPA in tap, mineral water and in plastic samples. The developed sensor was integrated into a PMMA case connected to the potentiostat to achieve complete isolation and a practical measurement system
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  Electropolymerization growth of an ultrathin, compact, conductive and microporous (UCCM) polycarbazole membrane for high energy Li–S batteries

  Guo, Dong; Li, Xiang; Ming, Fangwang; Zhou, Zongyao; Liu, Huifang; Hedhili, Mohamed N.; Tung, Vincent; Alshareef, Husam N.; Li, Yangxing; Lai, Zhiping (Nano Energy, Elsevier BV, 2020-04-11) [Article]

  Rationally constructing an interlayer to suppress the lithium polysulfide (LiPS) shuttling but allow fast transport of Li-ions is of great significance for high-density Li–S batteries. Despite numerous nanomaterials have been explored, an effective approach to fabricate an ideal interlayer is still elusive. Herein, we developed a new electropolymerization strategy to grow in-situ a polycarbazole-type interlayer with a number of merits to boost the reversible capacity. Firstly, the membrane is microporous but compact with uniform 0.82 nm nanochannels that can effectively suppress the diffusion of polysulfide species. Secondly, using the CNT (700 nm) as conductive substrate, the electropolymerized membrane is ultrathin (60 nm), which facilitates fast transport of lithium ions and rate performance. Thirdly, the membrane is electron conductive (23 S m−1) that benefits the charge transfer and redox reaction. Li–S batteries configured with such an UCCM type of interlayer have showed enhanced sulfur utilization by threefold, with a reversible capacity of 920 mA h g−1 after 600 cycles at 0.2 C, and a high areal density of 10 mAh cm−2 at 11.2 mg cm−2 sulfur loading. A safer lithium-ion sulfur full-cell with lithiated graphite anode demonstrated a stable capacity over 4 mAh cm−2 under a low electrolyte/sulfur ratio of ∼10 μL mg−1

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