Brush seal numerical simulation: Concepts and advances

The development of the brush seal is considered to be most promising among the advanced type seals that are presently in use in the high speed turbomachinery. The brush is usually mounted on the stationary portions of the engine and has direct contact with the rotating element, in the process of limiting the 'unwanted' leakage flows between stages, or various engine cavities. This type of sealing technology is providing high (in comparison with conventional seals) pressure drops due mainly to the high packing density (around 100 bristles/sq mm), and brush compliance with the rotor motions. In the design of modern aerospace turbomachinery leakage flows between the stages must be minimal, thus contributing to the higher efficiency of the engine. Use of the brush seal instead of the labyrinth seal reduces the leakage flow by one order of magnitude. Brush seals also have been found to enhance dynamic performance, cost less, and are lighter than labyrinth seals. Even though industrial brush seals have been successfully developed through extensive experimentation, there is no comprehensive numerical methodology for the design or prediction of their performance. The existing analytical/numerical approaches are based on bulk flow models and do not allow the investigation of the effects of brush morphology (bristle arrangement), or brushes arrangement (number of brushes, spacing between them), on the pressure drops and flow leakage. An increase in the brush seal efficiency is clearly a complex problem that is closely related to the brush geometry and arrangement, and can be solved most likely only by means of a numerically distributed model

Flows in Pinned Arrays Simulating Brush Seals

Flows through idealized pin arrays were investigated using an unstructured grid finite difference model and the simplified Ergun model to predict leakage flows and pressure drops in brush seals. The models are in good agreement in the laminar region with departures in the laminar-turbulent transition region defined by the simplified Ergun model. No local disturbances in the velocity or pressure fields, symptomatic of turbulence were found in the numerical results. The simplified model failed to predict the pressure drop of a 32-pin anisotropic array. Transitional and anisotropic behavior require

Magnetization in AIIIBV semiconductor heterostructures with the depletion layer of manganese

The magnetic moment and magnetization in GaAs/Ga$_{0.84}$In$_{0.16}$As/GaAs heterostructures with Mn deluted in GaAs cover layers and with atomically controlled Mn $\delta$-layer thicknesses near GaInAs-quantum well ($\sim$3 nm) in temperature range T=(1.8-300)K in magnetic field up to 50 kOe have been investigated. The mass magnetization all of the samples of GaAs/Ga$_{0.84}$In$_{0.16}$As/GaAs with Mn increases with the increasing of the magnetic field that pointed out on the presence of low-dimensional ferromagnetism in the manganese depletion layer of GaAs based structures. It has been estimated the manganese content threshold at which the ferromagnetic ordering was found.Comment: 8 pages, 3 figure

Возможности применения расчета теории очередей с целью управления в реальном времени

Possibilities of using mathematical models of the theory of queues for the purpose of control of processes of discrete productions modeled by it in real time are investigated. As a model example, a system for managing the rearrangements of service items in queues was considered. For the analysis the methods of calculation of BMAP-controlled systems and the methods of the theory of recovery on periods of employment for queues with vacancies of requirements were used.As a result of research it is found out that mathematical modeling in the theory of queues can be used for simulation of discrete production for the purpose of design and the production analysis, but cannot be used for management of the modeled processes in real time.Исследованы возможности использования математических моделей теории очередей с целью управления в реальном времени моделируемыми ней процессами дискретных производств. В качестве модельного примера рассматривалась система управления перестановками предметов обслуживания в очередях. Для анализа были использованы методы расчета управляемых BMAP систем и методы теории восстановления на периодах занятости для очередей с вакансиями требований.В результате исследования выяснено, что математическое моделирование в теории очередей может быть использовано для имитационного моделирования дискретного производства с целью проектирования и производственного анализа, но не может быть использовано для управления моделируемыми процессами в реальном времени

Antitumor activity of the novel pyridine derivative

The study aim was to explore a toxicological property and antitumor action of the novel pyridine derivative LHT-17-19 in cell culture and on experimental models of lung cancer in mic

Magnetization in AIIIBV semiconductor heterostructures with the depletion layer of manganese

The magnetic moment and magnetization in GaAs/Ga₀.₈₄In₀.₁₆As/GaAs heterostructures with Mn deluted in GaAs cover layers and with atomically controlled Mn δ-layer thicknesses near GaInAs-quantum well (~3 nm) in temperature range T = 1.8–300 K in magnetic field up to 50 kOe have been investigated. The mass magnetization all of the samples of GaAs/Ga₀.₈₄In₀.₁₆As/GaAs with Mn increases with the increasing of the magnetic field that pointed out on the presence of low-dimensional ferromagnetism in the manganese depletion layer of GaAs based structures. It has been estimated the manganese content threshold at which the ferromagnetic ordering was found

Инфракрасная навигация в годы войны

The first samples of domestic infrared (hereinafter-IR) navigation devices were created in the late 30-ies of XX century in NII‑9 (Leningrad) and VEI (Moscow). Since the beginning of 1941 their production for the Navy and Air Force was organized, as the article describes in detail. After the war, the development of IR devices continued resulting in full coverage of the range of electromagnetic waves.Первые образцы отечественных инфракрасных (ИК) навигационных приборов были созданы в конце 30-х годов ХХ века в НИИ‑9 (Ленинград) и ВЭИ (Москва). С начала 1941 года организован их выпуск для флота и авиации, о чем подробно рассказывает статья. В послевоенное время это направление продолжало развиваться. В результате сейчас российские системы визуализации способны охватить весь диапазон электромагнитных волн

Полный лечебный патоморфоз рака желудка после одного цикла неоадъювантной химиотерапии по схеме FLOT (клиническое наблюдение)

Background. Gastric cancer is the 5th most common cancer and the 3rd leading cause of cancer death globally. In Russia, gastric cancer is the 2-nd leading cause of death (10.7 %). Surgery in combination with perioperative/adjuvant chemotherapy is the standard treatment for locally advanced gastric cancer. Four cycles of neoadjuvant chemotherapy and 4 cycles of adjuvant chemotherapy with the FLOT regimen is the most widely used treatment modality. The basis for the widespread use of this chemotherapy regimen was the results of a large randomized FLOT4 trial, according to which the perioperative FLOT regimen showed greater efficacy compared to the ECF regimen.The aim of the study was to demonstrate the feasibility of achieving patholopgical complete response and long-term remission after one course of neoadjuvant chemotherapy with FLOT regimen in a patient with locally advanced gastric cancer.Case description. A 69-year-old patient presented to A. Tsyb Medical Radiological Research Centre with complaints of general weakness, moderate epigastric pain for 2 months. The examination revealed stage T3N0M0 IIA gastric cancer. The patient received one cycle of neoadjuvant chemotherapy with the FLOT regimen. Given the fact, that the patient developed massive bleeding from the tumor, it was decided to stop neoadjuvant treatment. Subtotal gastrectomy with D2 lymph node dissection was performed. Histological examination of the surgical specimen revealed pathological complete response (grade 1a according to the classification of K.Becker et al., 2003). The patient is alive with no signs of disease progression for more than 36 months after starting the treatment.Conclusion. This clinical case demonstrated personalized approach to the treatment of patients with locally advanced gastric cancer. Pathological complete response was achieved after one cycle of neoadjuvant chemotherapy. Актуальность. Среди злокачественных новообразований рак желудка занимает пятое место по заболеваемости и третье место по смертности в мире. По показателю смертности в России он занимает второе место (10,7 %). В России и многих зарубежных странах стандартом лечения местнораспространенного рака желудка является применение хирургического метода в комбинации с адъювантной или периоперационной химиотерапией. Наиболее часто применяется трехкомпонентная схема химиотерапии FLOT, назначаются по четыре цикла пред- и послеоперационно. Основанием для широкого внедрения данной методики химиотерапии послужили результаты крупного рандомизированного исследования FLOТ4, согласно которому периоперационная схема FLOT показала большую эффективность в сравнении со схемой ECF.Цель исследования ‒ демонстрация возможности достижения полного лечебного патоморфоза и длительной ремиссии в лечении пациента с местнораспространенным раком желудка после одного курса неоадъювантной полихимиотерапии по схеме FLOT.Описание клинического случая. Пациент В., 69 лет, обратился в МРНЦ им. А.Ф. Цыба с жалобами на общую слабость, умеренные боли в эпигастрии в течение 2 мес. При обследовании установлен диагноз: рак тела желудка сТ3N0M0 IIA стадии. Был проведен один цикл неоадъювантной химиотерапии по схеме FLOT. Вследствие того что у больного развилось массивное кровотечение из опухоли, было принято решение прекратить проведение неоадъювантной терапии и выполнить хирургическое лечение. Операция была выполнена в объеме дистальной субтотальной резекции желудка с лимфодиссекцией D2. При морфологическом исследовании удаленного препарата была зарегистрирована 1а степень лечебного патоморфоза (по классификации K. Becker, 2003). На момент анализа пациент жив без признаков прогрессирования опухоли в течение более 36 мес, находится под динамическим наблюдением.Заключение. В представленном клиническом наблюдении продемонстрировано достижение полного лечебного патоморфоза после одного цикла неоадъювантной химиотерапии, а также 3-летняя безрецидивная выживаемость пациента.