МОДЕЛИРОВАНИЕ ОТКАЗОВ В АВТОМАТИЗИРОВАННОЙ СИСТЕМЕ УПРАВЛЕНИЯ ВОЗДУШНЫМ СУДНОМ

This article is devoted to studying of fault diagnosis of an aircraft control surfaces using fault models to identify specific causes. Such failures as jamming, vibration, extreme run out and performance decrease are covered.It is proved that in case of an actuator failure or flight control structural damage, the aircraft performance decreases significantly. Commercial aircraft frequently appear in the areas of military conflicts and terrorist activity, where the risk of shooting attack is high, for example in Syria, Iraq, South Sudan etc. Accordingly, it is necessary to create and assess the fault model to identify the flight control failures.The research results demonstrate that the adequate fault model is the first step towards the managing the challenges of loss of aircraft controllability. This model is also an element of adaptive failure-resistant management model.The research considers the relationship between the parameters of an i th state of a control surface and its angular rate, also parameters classification associated with specific control surfaces in order to avoid conflict/inconsistency in the determination of a faulty control surface and its condition.The results of the method obtained in this article can be used in the design of an aircraft automated control system for timely identification of fault/failure of a specific control surface, that would contribute to an effective role aimed at increasing the survivability of an aircraft and increasing the acceptable level of safety due to loss of control.Исследуется вопрос управляемости воздушного судна при допущении отказов органов управления (ОУ) путем моделирования характеристики управления с учетом особенности его системы автоматического управления. Приводятся виды отказов органов управления самолетом, такие как клинение, колебание, увод в крайнее положение и снижение производительности.Обосновано, что при допущении отказа вследствие потери привода (actuator) или разрушения конструкции ОУ эксплуатационно-летные характеристики самолета значительно ухудшаются. Гражданские воздушные суда (ВС) нередко могут находиться в зонах конфликтов и террористической активности, где не исключена вероятность обстрела, например, в Сирии, Ираке, Южном Судане и т. д. Следовательно, необходима модель отказов, способная идентифицировать отказы вследствие разрушения конструкций и отказов компонентов, органов управления.Результаты данного исследования показывают, что адекватная модель отказов является первым шагом в сторону решения задач потери управляемости ВС при допущении отказов и частью дальнейшей адаптационной модели управления. Таким образом, можно обеспечить высокую эксплуатационную живучесть и надежность ВС, а также экономически рационально повысить уровень безопасности его полетов (БП).Результаты исследования, полученные в данной статье на основе моделирования нелинейного движения ВС при стабилизации углов по тангажу и крену, позволят в дальнейшем разработать алгоритм своевременного выявления отказа конкретной ОУ, который будет использован при проектировании автоматизированной системы управления самолета и на стадии разработки перспективных бортовых систем управления (БСУ). Внедрение полученных результатов позволит эффективно повысить отказоустойчивость ОУ, надежность элементов конструкции ЛА и поддерживать приемлемый уровень БП при допущении частичной или полной потери управляемости ВС из-за разрушения конструктивных компонентов органов управления и отказов ОУ ВС

Клинический случай этапного лечения комбинированных осложнений ортотопической трансплантации печени

Hepatic artery thrombosis (HAT) following liver transplantation (LT) is a severe life-threatening complication that can lead to graft loss and mortality after LT. According to different reports, HAT incidence ranges from 2% to 9%. Modern endovascular and radiosurgical techniques allow for minimally invasive liver graft revascularization. Nonetheless, a major consequence of even a successful revascularization is ischemic cholangiopathy, which can lead to ischemic biliary strictures and anastomotic leak. The paper presents a clinical case of long-term complex treatment of combined complications of LT using minimally invasive endovascular and endoscopic techniques.Тромбоз артерии трансплантата печени - тяжелое осложнение, которое может привести к потере трансплантата и смерти реципиента. По данным различных авторов, частота возникновения тромбозов колеблется от 2 до 9%. Современные эндоваскулярные рентгенохирургические технологии позволяют малоинвазивно выполнить реваскуляризацию печеночного трансплантата. В то же время серьезным последствием даже успешной реваскуляризации является ишемическая холангиопатия, которая может приводить к формированию ишемических билиарных стриктур и несостоятельности анастомоза. В статье представлен клинический случай длительного комплексного лечения комбинированных осложнений трансплантации печени с использованием малоинвазивных эндоваскулярных и эндоскопических технологий

Second asymptomatic carotid surgery trial (ACST-2): a randomised comparison of carotid artery stenting versus carotid endarterectomy

Background: Among asymptomatic patients with severe carotid artery stenosis but no recent stroke or transient cerebral ischaemia, either carotid artery stenting (CAS) or carotid endarterectomy (CEA) can restore patency and reduce long-term stroke risks. However, from recent national registry data, each option causes about 1% procedural risk of disabling stroke or death. Comparison of their long-term protective effects requires large-scale randomised evidence. Methods: ACST-2 is an international multicentre randomised trial of CAS versus CEA among asymptomatic patients with severe stenosis thought to require intervention, interpreted with all other relevant trials. Patients were eligible if they had severe unilateral or bilateral carotid artery stenosis and both doctor and patient agreed that a carotid procedure should be undertaken, but they were substantially uncertain which one to choose. Patients were randomly allocated to CAS or CEA and followed up at 1 month and then annually, for a mean 5 years. Procedural events were those within 30 days of the intervention. Intention-to-treat analyses are provided. Analyses including procedural hazards use tabular methods. Analyses and meta-analyses of non-procedural strokes use Kaplan-Meier and log-rank methods. The trial is registered with the ISRCTN registry, ISRCTN21144362. Findings: Between Jan 15, 2008, and Dec 31, 2020, 3625 patients in 130 centres were randomly allocated, 1811 to CAS and 1814 to CEA, with good compliance, good medical therapy and a mean 5 years of follow-up. Overall, 1% had disabling stroke or death procedurally (15 allocated to CAS and 18 to CEA) and 2% had non-disabling procedural stroke (48 allocated to CAS and 29 to CEA). Kaplan-Meier estimates of 5-year non-procedural stroke were 2·5% in each group for fatal or disabling stroke, and 5·3% with CAS versus 4·5% with CEA for any stroke (rate ratio [RR] 1·16, 95% CI 0·86–1·57; p=0·33). Combining RRs for any non-procedural stroke in all CAS versus CEA trials, the RR was similar in symptomatic and asymptomatic patients (overall RR 1·11, 95% CI 0·91–1·32; p=0·21). Interpretation: Serious complications are similarly uncommon after competent CAS and CEA, and the long-term effects of these two carotid artery procedures on fatal or disabling stroke are comparable. Funding: UK Medical Research Council and Health Technology Assessment Programme

A murine living skin equivalent amenable to live cell imaging: analysis of the roles of connexins in the epidermis

Three-dimensional (3D) organotypic models are increasingly used to study the aspects of epidermal organisation and cutaneous wound-healing events. However, these are largely dependent on laborious histological analysis and immunohistochemical approaches. Despite the large resource of transgenic and knockout mice harboring mutations relevant to skin disorders, few organotypic mouse skin models are available. We have developed a versatile in vitro 3D organotypic mouse skin equivalent that reflects epidermal organisation in vivo. The system is optically transparent and ideally suited to real-time analysis using a variety of integrated in situ imaging techniques. As a paradigm for coordination of cellular events, the epidermal gap junction network was investigated and the model displayed predominant connexin 43 (Cx43) expression in basal proliferating cells and Cx26 and Cx30 expression in differentiated keratinocytes. We show that attenuation of Cx43-mediated communication by a Cx mimetic peptide enhanced wound closure rates in keratinocyte monocultures and in the living skin equivalent system, emphasising the utility of the model to systematically unravel the molecular mechanisms underlying epidermal morphogenesis, assess promising therapeutic strategies, and reduce animal experimentation. Furthermore, we visualise epidermal regeneration following injury in real time, thereby facilitating avenues to explore distinctive modes of wound re-epithelialisation in a non-invasive manner

Liposomes loaded with diglyceride esters of methotrexate and mephalan studies on stability and hemocompatibility

peer reviewe

Liposomes loaded with diglyceride esters of methotrexate and melphalan: studies on stability and hemocompatibility

peer reviewe

Liver cell lines for the study of hepatocyte functions and immunological response.

BACKGROUND: Liver cell lines closely resembling primary hepatocyte are essential for research on hepatitis viruses and hepatocyte function. Currently used cell lines are derived from hepatic tumours and have altered gene expression. AIMS: The generation and characterisation of novel human hepatocyte lines (HHLs) derived from healthy human liver, retaining the primary hepatocyte phenotype. RESULTS: Primary hepatocytes were immortalised with Moloney's mouse leukaemia virus expressing E6 and E7 proteins of human papillomavirus, and cultures propagated long-term. All HHLs contained markers of hepatocyte and biliary phenotype (cytokeratins 7, 8, 18 and 19), Cytochrome P450 and albumin. The HHLs did not express high levels of p53 or alpha-fetoprotein. When grown in a collagen sandwich culture, or at the air-liquid interface, HHLs were maintained as monolayer whereas Huh-7 and HepG2 formed thick layers. All HHLs showed increased capacity to bind recombinant hepatitis C virus-like particles in comparison with Huh-7 and HepG2. We also demonstrate that HHLs contained active gap junctions, and that the cells respond to stimulation with IFN-alpha by upregulation of major histocompatibility complex (MHC)-I and -II. CONCLUSIONS: These HHLs retain primary hepatocyte phenotype and should be useful for investigating mechanisms of entry and replication of hepatotropic viruses, and should also be valuable in the study of hepatocyte biology and pathology