Data analytics for stochastic control and prognostics in cyber-physical systems

In this dissertation, several novel cyber fault diagnosis and prognosis and defense methodologies for cyber-physical systems have been proposed. First, a novel routing scheme for wireless mesh network is proposed. An effective capacity estimation for P2P and E2E path is designed to guarantee the vital transmission safety. This scheme can ensure a high quality of service (QoS) under imperfect network condition, even cyber attacks. Then, the imperfection, uncertainties, and dynamics in the cyberspace are considered both in system model and controller design. A PDF identifier is proposed to capture the time-varying delays and its distribution. With the modification of traditional stochastic optimal control using PDF of delays, the assumption of full knowledge of network imperfection in priori is relaxed. This proposed controller is considered a novel resilience control strategy for cyber fault diagnosis and prognosis. After that, we turn to the development of a general framework for cyber fault diagnosis and prognosis schemes for CPSs wherein the cyberspace performance affect the physical system and vice versa. A novel cyber fault diagnosis scheme is proposed. It is capable of detecting cyber fault by monitoring the probability of delays. Also, the isolation of cyber and physical system fault is achieved with cooperating with the traditional observer based physical system fault detection. Next, a novel cyber fault prognosis scheme, which can detect and estimate cyber fault and its negative effects on system performance ahead of time, is proposed. Moreover, soft and hard cyber faults are isolated depending on whether potential threats on system stability is predicted. Finally, one-class SVM is employed to classify healthy and erroneous delays. Then, another cyber fault prognosis based on OCSVM is proposed --Abstract, page iv

Effect of Eccentricity on Annulus Pressure of Aerated Drilling

In the past two decades, aerated drilling has been applied to improving recovery of the low permeability oil and gas reservoirs at home and abroad. This technology can improve the level of exploration and development, reduce the cost of drilling and protect reservoir. Because of its advantages, aerated drilling has been developed and promoted rapidly. And its theoretical study has also been further developed. In this paper, the impact of the eccentric drill string to annular multiphase fluid in aerated drilling was studied. Based on mathematical solution of eccentric annuli, combined with multiphase flow control equations and flow law, aerated drilling eccentric annulus pressure formula was derived. Under the condition of Concentricity and different degrees of eccentricity, the eccentric annulus pressure were calculated. The distribution law of annulus pressure with depth and the influence law of the eccentricity to annulus pressure were analyzed. Key words: Aerated drilling, Eccentric annuli; Annulus pressur

Numerical Simulation of Effect of Eccentricity on Annulus Pressure of Aerated Drilling

Aerated drilling can effectively solve the mud leakage, reservoir pollution and the critical question of the effect of productivity. It also can protect, find and correctly evaluate oil and gas resources. The technology of aerated drilling is applied to detailed exploration and step-out well of oil and gas field of low pressure, this technology has wide applications. Based on the previous researches, the effect of drill string under the condition of eccentricity on annulus pressure is considered in this paper. After in-depth investigations, annulus pressure of concentric and eccentric conditions are analyzed through the CFD numerical simulation, the distribution law of pressure of eccentric annulus along well depth is expounded. The following conclusions can be showed through the CFD numerical simulation: the annulus pressure of aerated drilling follows curve, the pressure decreases gradually from the bottom to wellhead. The pressure does not vary abruptly in the position of changing area of annulus cross-section, the reason is that the gravitational pressure drop plays the leading position in the annulus pressure drop. Liquid is incompressible fluid, although the gas volume is changed, the density of gas is small relative to the density of liquid, so the density of drilling fluid changes little in the variable cross-section. Under the same conditions, the flow pressure drop of eccentric annulus is less than concentric annulus.Key words: Aerated drilling; Concentric annulus; Eccentric annulus; Annulus pressure; CFD numerical simulatio

Changes in late adolescents’ trust before and during the COVID-19 pandemic

Trust is crucial to the public’s compliance with policies and rules released by governments, particularly in times of the coronavirus disease 2019 (COVID-19) pandemic. However, it remains unclear whether and to what extent late adolescents’ interpersonal and institutional trust fluctuated from the pre-COVID-19 pandemic to the lasting phase of the COVID-19 pandemic. The present study uses three-wave longitudinal data from the Youth Got Talent (YGT) project to address this gap (n = 1,423; 43% boys; Mage= 17.85, SD = 1.95). Latent basis growth curve models showed that interpersonal trust remained relatively stable over time. In contrast, institutional trust temporarily increased from pre-COVID-19 pandemic (Fall 2019) to the initial phase of the COVID-19 pandemic (Spring 2020) and subsequently, decreased during the lasting phase of the COVID-19 pandemic (Fall 2020). These results enhance our understanding of trust among late adolescents and have implications for policies aiming to manage the COVID-19 pandemic

ImageCAS: A Large-Scale Dataset and Benchmark for Coronary Artery Segmentation based on Computed Tomography Angiography Images

Cardiovascular disease (CVD) accounts for about half of non-communicable diseases. Vessel stenosis in the coronary artery is considered to be the major risk of CVD. Computed tomography angiography (CTA) is one of the widely used noninvasive imaging modalities in coronary artery diagnosis due to its superior image resolution. Clinically, segmentation of coronary arteries is essential for the diagnosis and quantification of coronary artery disease. Recently, a variety of works have been proposed to address this problem. However, on one hand, most works rely on in-house datasets, and only a few works published their datasets to the public which only contain tens of images. On the other hand, their source code have not been published, and most follow-up works have not made comparison with existing works, which makes it difficult to judge the effectiveness of the methods and hinders the further exploration of this challenging yet critical problem in the community. In this paper, we propose a large-scale dataset for coronary artery segmentation on CTA images. In addition, we have implemented a benchmark in which we have tried our best to implement several typical existing methods. Furthermore, we propose a strong baseline method which combines multi-scale patch fusion and two-stage processing to extract the details of vessels. Comprehensive experiments show that the proposed method achieves better performance than existing works on the proposed large-scale dataset. The benchmark and the dataset are published at https://github.com/XiaoweiXu/ImageCAS-A-Large-Scale-Dataset-and-Benchmark-for-Coronary-Artery-Segmentation-based-on-CT.Comment: 17 pages, 12 figures, 4 table

Chitosan-salvianolic acid B coating on the surface of nickel-titanium alloy inhibits proliferation of smooth muscle cells and promote endothelialization

Introduction: Intracranial stents are of paramount importance in managing cerebrovascular disorders. Nevertheless, the currently employed drug-eluting stents, although effective in decreasing in-stent restenosis, might impede the re-endothelialization process within blood vessels, potentially leading to prolonged thrombosis development and restenosis over time.Methods: This study aims to construct a multifunctional bioactive coating to enhance the biocompatibility of the stents. Salvianolic acid B (SALB), a bioactive compound extracted from Salvia miltiorrhiza, exhibits potential for improving cardiovascular health. We utilized dopamine as the base and adhered chitosan-coated SALB microspheres onto nickel-titanium alloy flat plates, resulting in a multifunctional drug coating.Results: By encapsulating SALB within chitosan, the release period of SALB was effectively prolonged, as evidenced by the in vitro drug release curve showing sustained release over 28 days. The interaction between the drug coating and blood was examined through experiments on water contact angle, clotting time, and protein adsorption. Cellular experiments showed that the drug coating stimulates the proliferation, adhesion, and migration of human umbilical vein endothelial cells.Discussion: These findings indicate its potential to promote re-endothelialization. In addition, the bioactive coating effectively suppressed smooth muscle cells proliferation, adhesion, and migration, potentially reducing the occurrence of neointimal hyperplasia and restenosis. These findings emphasize the exceptional biocompatibility of the newly developed bioactive coating and demonstrate its potential clinical application as an innovative strategy to improve stent therapy efficacy. Thus, this coating holds great promise for the treatment of cerebrovascular disease

Energy deficiency promotes rhythmic foraging behavior by activating neurons in paraventricular hypothalamic nucleus

BackgroundDysregulation of feeding behavior leads to a variety of pathological manifestations ranging from obesity to anorexia. The foraging behavior of animals affected by food deficiency is not fully understood.MethodsHome-Cage system was used to monitor the behaviors. Immunohistochemical staining was used to monitor the trend of neuronal activity. Chemogenetic approach was used to modify neuronal activity.ResultsWe described here a unique mouse model of foraging behavior and unveiled that food deprivation significantly increases the general activities of mice with a daily rhythmic pattern, particularly foraging behavior. The increased foraging behavior is potentiated by food cues (mouthfeel, odor, size, and shape) and energy deficit, rather than macronutrient protein, carbohydrate, and fat. Notably, energy deficiency increases nocturnal neuronal activity in paraventricular hypothalamic nucleus (PVH), accompanying a similar change in rhythmic foraging behavior. Activating neuronal activity in PVH enhances the amplitude of foraging behavior in mice. Conversely, inactivating neuronal activity in PVH decreases the amplitude of foraging behavior and impairs the rhythm of foraging behavior.DiscussionThese results illustrate that energy status and food cues regulate the rhythmic foraging behavior via PVH neuronal activity. Understanding foraging behavior provides insights into the underlying mechanism of eating-related disorders

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead