•The CO2 huff-n-puff for EOR in the Bakken is investigated.•CO2 molecular diffusivity is a significant factor.•Sensitivity studies are performed to quantify the key parameters.•More heterogeneity is ...much favorable for the CO2 huff-n-puff process.
The combination of horizontal drilling and multi-stage hydraulic fracturing have boosted the oil production from Bakken tight oil reservoirs. However, the primary oil recovery factor is very low due to the extremely tight formation, resulting in substantial volumes of oil still remaining in place. Hence, it is important to investigate the potential of applying enhanced oil recovery methods to increase oil recovery in the Bakken formation. Although carbon dioxide (CO2) is widely used in conventional reservoirs to improve oil recovery, it is a new subject and not well-understood in unconventional oil reservoirs such as the Bakken formation. In this paper, we use numerical reservoir simulation to model CO2 injection as a huff-n-puff process with typical reservoir and fracture properties from the Bakken formation. Effects of CO2 molecular diffusion, number of cycle, fracture half-length, permeability and reservoir heterogeneity on the well performance of CO2 huff-n-puff are examined in detail. The results show that the CO2 diffusion plays a significant role in improving oil recovery from tight oil reservoirs, which cannot be neglected in the reservoir simulation model. Additionally, the tight oil formation with lower permeability, longer fracture half-length, and more heterogeneity is more favorable for the CO2 huff-n-puff process. This work can provide a better understanding of the physical mechanisms and key parameters affecting the effectiveness of CO2 injection for enhanced oil recovery in the Bakken formation.
Relative position encoding (RPE) is important for transformer to capture sequence ordering of input tokens. General efficacy has been proven in natural language processing. However, in computer ...vision, its efficacy is not well studied and even remains controversial, e.g., whether relative position encoding can work equally well as absolute position? In order to clarify this, we first review existing relative position encoding methods and analyze their pros and cons when applied in vision transformers. We then propose new relative position encoding methods dedicated to 2D images, called image RPE (iRPE). Our methods consider directional relative distance modeling as well as the interactions between queries and relative position embeddings in self-attention mechanism. The proposed iRPE methods are simple and lightweight. They can be easily plugged into transformer blocks. Experiments demonstrate that solely due to the proposed encoding methods, DeiT 21 and DETR 1 obtain up to 1.5% (top-1 Acc) and 1.3% (mAP) stable improvements over their original versions on ImageNet and COCO respectively, without tuning any extra hyperparameters such as learning rate and weight decay. Our ablation and analysis also yield interesting findings, some of which run counter to previous understanding. Code and models are open-sourced at https://github.com/microsoft/Cream/tree/main/iRPE.
Numerous reports of vascular events after an initial recovery from COVID-19 form our impetus to investigate the impact of COVID-19 on vascular health of recovered patients. We found elevated levels ...of circulating endothelial cells (CECs), a biomarker of vascular injury, in COVID-19 convalescents compared to healthy controls. In particular, those with pre-existing conditions (e.g., hypertension, diabetes) had more pronounced endothelial activation hallmarks than non-COVID-19 patients with matched cardiovascular risk. Several proinflammatory and activated T lymphocyte-associated cytokines sustained from acute infection to recovery phase, which correlated positively with CEC measures, implicating cytokine-driven endothelial dysfunction. Notably, we found higher frequency of effector T cells in our COVID-19 convalescents compared to healthy controls. The activation markers detected on CECs mapped to counter receptors found primarily on cytotoxic CD8
T cells, raising the possibility of cytotoxic effector cells targeting activated endothelial cells. Clinical trials in preventive therapy for post-COVID-19 vascular complications may be needed.
This paper studies the scheduling of autonomous mobile robots (AMRs) at hospitals where the stochastic travel times and service times of AMRs are affected by the surrounding environment. The routes ...of AMRs are planned to minimize the daily cost of the hospital (including the AMR fixed cost, penalty cost of violating the time window, and transportation cost). To efficiently generate high-quality solutions, some properties are identified and incorporated into an improved tabu search (I-TS) algorithm for problem-solving. Experimental evaluations demonstrate that the I-TS algorithm outperforms existing methods by producing high-quality solutions. Based on the characteristics of healthcare requests and the AMR working environment, scheduling AMRs reasonably can effectively provide medical services, improve the utilization of medical resources, and reduce hospital costs.
We reply to the comments raised by Phung and Lintz in the above comment to conclude that the results in the letter published in IEEE Photonics Technology Letters might have been misinterpreted due to ...the underestimiation of the RIN-to-phase-noise conversion in the laser when pump modulation is applied. Care should be taken when one uses pump modulation technique to evaluate the RIN-to-phase-noise conversion in the photodiode.
Dissipative Kerr solitons (DKS) in high-Q microresonators have attracted considerable attention for their broadband optical frequency combs and ultra-short pulse generation. Owing to thermal effects, ...complicated tuning strategies are required to generate and sustain the single-soliton state in microresonators. In this paper, we propose a novel microresonator scheme based on the Fabry-Pérot fiber resonator and single-layer graphene saturable absorber (SA) and demonstrate that this design allows deterministic single-soliton generation without frequency tuning and has strong robustness against pump perturbation. The soliton range and thermal instability of the proposed device are also discussed. This work facilitates a novel nonlinear platform connecting high-Q microresonators and conventional SA-assisted mode-locking operations.
Frank–Kasper (F-K) and quasicrystal phases were originally identified in metal alloys and only sporadically reported in soft materials. These unconventional sphere-packing schemes open up ...possibilities to design materials with different properties. The challenge in soft materials is how to correlate complex phases built from spheres with the tunable parameters of chemical composition and molecular architecture. Here, we report a complete sequence of various highly ordered mesophases by the self-assembly of specifically designed and synthesized giant surfactants, which are conjugates of hydrophilic polyhedral oligomeric silsesquioxane cages tethered with hydrophobic polystyrene tails. We show that the occurrence of these mesophases results from nanophase separation between the heads and tails and thus is critically dependent on molecular geometry. Variations in molecular geometry achieved by changing the number of tails from one to four not only shift compositional phase boundaries but also stabilize F-K and quasicrystal phases in regions where simple phases of spheroidal micelles are typically observed. These complex self-assembled nanostructures have been identified by combining X-ray scattering techniques and real-space electron microscopy images. Brownian dynamics simulations based on a simplified molecular model confirm the architecture-induced sequence of phases. Our results demonstrate the critical role of molecular architecture in dictating the formation of supramolecular crystals with “soft” spheroidal motifs and provide guidelines to the design of unconventional self-assembled nanostructures.
Advances in protein therapy are hindered by the poor stability, inadequate pharmacokinetic (PK) profiles, and immunogenicity of many therapeutic proteins. Polyethylene glycol conjugation (PEGylation) ...is the most successful strategy to date to overcome these shortcomings, and more than 10 PEGylated proteins have been brought to market. However, anti-PEG antibodies induced by treatment raise serious concerns about the future of PEGylated therapeutics. Here, we demonstrate a zwitterionic polymer network encapsulation technology that effectively enhances protein stability and PK while mitigating the immune response. Uricase modified with a comprehensive zwitterionic polycarboxybetaine (PCB) network exhibited exceptional stability and a greatly prolonged circulation half-life. More importantly, the PK behavior was unchanged, and neither anti-uricase nor anti-PCB antibodies were detected after three weekly injections in a rat model. This technology is applicable to a variety of proteins and unlocks the possibility of adopting highly immunogenic proteins for therapeutic or protective applications.
The discovery of two-dimensional (2D) material graphene has opened a door towards a class of layered novel nanomaterials with unique photonic and optoelectronic properties. Recently many new 2D ...materials have been reported, including topological insulators (TIs), transition metal dichalcogenides (TMDs) and black phosphorus (BP). These materials have been demonstrated high optical nonlinearity and Pauli blocking used as saturable absorbers (SAs) in pulsed lasers. In this paper, we summarize the current specifications from these 2D materials based mode-locked and Q-switched lasers. The laser performance in operating wavelength, optical bandwidth, repetition rate and pulse energy is reviewed. Finally future perspective is suggested.
•Mode-locked and Q-switched lasers based on three 2D materials are reviewed.•Best specifications of bandwidth, repetition rate and pulse energy are summarized.•Material basic properties, fabrication and characterization are also introduced.
Industry 4.0 technologies create a connected ecosystem that allows for real-time monitoring, control, and optimization. This enables the manufacturing industry to move the ultimate goal of their ...businesses from lean to leagile. Then, to meet the needs of leagile manufacturing, an integrated production planning and scheduling system is needed. The academic world responds to the need by the growth of papers. Many methodologies, models, frameworks, and methods have been proposed. Literature abounds on classifying them, yet it remains inconclusive mainly on their applicability to Industry 4.0. In this regard, this paper conducts a literature review aiming to show the state of the art and discover the most promising production planning and scheduling method for Industry 4.0 among the many. Lastly, on the basis of this study, recommendations on possible future research directions are provided for researchers, and the design of the next-generation production planning and scheduling system for Industry 4.0 is also suggested.
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