Simulation and Optimization of Multi-period Steam Cracking Process

Hydrocarbon steam cracking is the most important process for producing industrial chemicals such as olefin and aromatics. Steam cracking modelling and optimization is an effective way for increasing production and saving energy. In this chapter, multi-scale modelling and elementary reaction networks are established and used in the modelling and optimization of steam cracking. However, the large scale of the optimization model makes it difficult to obtain a solution. Thus, a surrogate coke thickness model for long-term steam cracking is proposed in this chapter to remove the connection between different periods of steam cracking process. By so doing, a parallel simulation can be used to accelerate optimization. An industrial case study showed optimization time to be significantly reduced from 17.78 hours to 2.08 hours using multi-period optimization with parallel simulation and the surrogate coke thickness model. It has been shown that a 0.62% increase in ethylene yield can be obtained via operating condition optimization, which demonstrates the effectiveness of the multi-scale steam cracking model and multi-period optimization with parallel simulation

DCCTNet: Kidney tumors segmentation based on dual-level combination of CNN and transformer

The hybrid model of CNN(Convolution Neural Networks) and Transformer is a popular method in segmenting kidney images, but most existing hybrid models directly fused local features from CNN with global features from Transformer, ignoring the issue of semantic gaps between distinct features. Furthermore, feature fusion is typically performed solely at the feature level, without considering alignment at the mask (prediction map) level. To address these limitations, we propose a novel segmentation method called Dual-level Combination of CNN and Transformers Network (DCCTNet). Specifically, we select similar features from both CNN and Transformer to reduce semantic gaps at the feature level. Additionally, we further utilize the global information of the Transformers by reducing the difference between the prediction maps in the coding stage at the mask level. We evaluate DCCTNet on the KiTS19 dataset, achieving 97.3% dice score for kidneys segmentation and 81.2% dice score for kidney tumors segmentation, respectively. https://github.com/hou-bz/DCCTNet

Antagonist Effect of Triptolide on AKT Activation by Truncated Retinoid X Receptor-alpha

Background: Retinoid X receptor-alpha (RXR alpha) is a key member of the nuclear receptor superfamily. We recently demonstrated that proteolytic cleavage of RXR alpha resulted in production of a truncated product, tRXR alpha, which promotes cancer cell survival by activating phosphatidylinositol-3-OH kinase (PI3K)/AKT pathway. However, how the tRXR alpha-mediated signaling pathway in cancer cells is regulated remains elusive. Methodology/Principal Findings: We screened a natural product library for tRXR alpha targeting leads and identified that triptolide, an active component isolated from traditional Chinese herb Trypterygium wilfordii Hook F, could modulate tRXR alpha-mediated cancer cell survival pathway in vitro and in animals. Our results reveal that triptolide strongly induces cancer cell apoptosis dependent on intracellular tRXR alpha expression levels, demonstrating that tRXR alpha serves as an important intracellular target of triptolide. We show that triptolide selectively induces tRXR alpha degradation and inhibits tRXR alpha-dependent AKT activity without affecting the full-length RXR alpha. Interestingly, such effects of triptolide are due to its activation of p38. Although triptolide also activates Erk1/2 and MAPK pathways, the effects of triptolide on tRXR alpha degradation and AKT activity are only reversed by p38 siRNA and p38 inhibitor. In addition, the p38 inhibitor potently inhibits tRXR alpha interaction with p85 alpha leading to AKT inactivation. Our results demonstrate an interesting novel signaling interplay between p38 and AKT through tRXR alpha mediation. We finally show that targeting tRXR alpha by triptolide strongly activates TNF alpha death signaling and enhances the anticancer activity of other chemotherapies Conclusions/Significance: Our results identify triptolide as a new xenobiotic regulator of the tRXR alpha-dependent survival pathway and provide new insight into the mechanism by which triptolide acts to induce apoptosis of cancer cells. Triptolide represents one of the most promising therapeutic leads of natural products of traditional Chinese medicine with unfortunate side-effects. Our findings will offer new strategies to develop improved triptolide analogs for cancer therapy.National Natural Science Foundation of China [NSFC: 30971445, 90913015, 91129302]; NSFC/Hong Kong Research Grants Council [NSFC/RGC: 30931160431/N_HKU 735/09]; Natural Science Foundation of Fujian Province [2009J01198

Planning-oriented optimization strategy for visualizing power distribution networks: from global to local

The spatial distribution of power facilities is uneven, thereby making the topology of geographical wiring diagrams (GWDs) based on the actual coordinates unclear. A single-line diagram has the advantage of a clear topology but it lacks spatial locations. A GWD has the advantage of accurate spatial locations but it lacks a clear topology. Visualizing distribution networks for planning requires both features. We proposed a new planning-oriented method for optimizing the visualization of distribution networks. From the global perspective, we proposed an improved force-directed (FD) algorithm by introducing a space restriction strategy and node–edge repulsion strategy to promote the expansion of the distance between distribution facilities within a limited buffer. We then constructed the constrained Delaunay triangulation to identify the compact districts (CDs) and used a genetic algorithm to optimize the parameters for the improved FD algorithm. A novel visualization evaluation indicator was also proposed for quantitatively assessing the visualizations. From a local perspective, the fisheye algorithm was used to optimize the CDs to further improve the visualization of the distribution network. We verified the proposed methods with real-world data. We used limited spatial displacement in exchange for maximum topology clarity to balance the accurate spatial location and topology clarity

A new method for sentiment classification in text retrieval

Abstract. Traditional text categorization is usually a topic-based task, but a subtle demand on information retrieval is to distinguish between positive and negative view on text topic. In this paper, a new method is explored to solve this problem. Firstly, a batch of Concerned Concepts in the researched domain is predefined. Secondly, the special knowledge representing the positive or negative context of these concepts within sentences is built up. At last, an evaluating function based on the knowledge is defined for sentiment classification of free text. We introduce some linguistic knowledge in these procedures to make our method effective. As a result, the new method proves better compared with SVM when experimenting on Chinese texts about a certain topic.

Endothelial Progenitor Cells for Ischemic Stroke: Update on Basic Research and Application

Ischemic stroke is one of the leading causes of human death and disability worldwide. So far, ultra-early thrombolytic therapy is the most effective treatment. However, most patients still live with varying degrees of neurological dysfunction due to its narrow therapeutic time window. It has been confirmed in many studies that endothelial progenitor cells (EPCs), as a kind of adult stem cells, can protect the neurovascular unit by repairing the vascular endothelium and its secretory function, which contribute to the recovery of neurological function after an ischemic stroke. This paper reviews the basic researches and clinical trials of EPCs especially in the field of ischemic stroke and addresses the combination of EPC application with new technologies, including neurovascular intervention, synthetic particles, cytokines, and EPC modification, with the aim of shedding some light on the application of EPCs in treating ischemic stroke in the future

Growth of AlGaN Film on Si (111) Substrate

At present, the applications of AlxGa1−xN are extensive, such as for visible-blind ultraviolet detectors, laser diodes, light emitting diodes (LEDs) and HEMTs. In this paper, Al0.25Ga0.75N and Al0.32Ga0.68N films have been grown on 2 in Si (iii) substrates by MOCVD. The low-temperature (6 K) photoluminescence (PL) spectrum and XRD rocking curve measurements have been employed to study the crystal quality of samples, and the phonon replica peak can be observed, which indicate that the samples have better quality in a small-localized region. The surface morphology of samples was investigated by AFM and the result of wavy surface agrees with the deduction from XRD rocking curve measurements. The sheet resistance mappings have been shown, and it indicates the nonuniformity of AlGaN film on Si (iii) will increase sharply as the Al content increases

Ultra-Thin Broadband Circular Polarization Conversion Metasurface for Full-Space Wavefront Manipulation Application

In this article, we introduced an ultra-thin broadband single-layer metasurface (MS) comprising an S-shaped resonator (SSR) structure enclosed by a circular cover adhered on a dielectric substrate. The MS exhibits remarkable capabilities in achieving simultaneous half-transmission and half-reflection for broadband circular polarization (CP) conversion, as well as full-space wavefront manipulation in the microwave frequency range. Through simulations and experiments, we demonstrated that the orthogonal CP coefficients for both transmission and reflection exceed 0.35 for normal incidence of left-handed circular polarizations (LCP) and right-handed circular polarizations (RCP) waves from 6.2 GHz to 15 GHz, with a relative bandwidth of about 87.1%. This results in a polarization conversion efficiency of approximately 22%, which approaches the theoretical limit (25%) of the single layer MS structure around 8 GHz. Moreover, utilizing the principle of geometrical phase modulation, the desired full 2π phase-shift of orthogonal CP waves in both transmission and reflection can be achieved by solely adjusting the orientation angle of the SSR structure. Numerical simulations substantiate this concept by demonstrating anomalous reflection and refraction, vortex beam generation, and planar focusing, showcasing the comprehensive control of wavefronts in all spatial directions. Our design offers valuable insights for the practical implementation of broadband full-space CP and wavefront manipulation in various applications