Improvement of the Sintered Surface and Bulk of the Product Via Differentiating Laser Sintering (Melting) Modes

Selective laser sintering (melting) enables using metal powdered materials to manufacture products of any geometrical complexity, requiring no preliminary costs to prepare processing equipment. However, quality of the sintered surface is often inadequate as against the product manufactured traditionally. Manufacturing a high quality product requires solution of such vital task as prediction of the sintered surface roughness. The authors address to the effect of laser sintering modes on roughness of the surface, sintered of copper powdered material PMS-l (IIMC-1). The dependence of roughness of the surface layer sintered of copper powder material PMS-l upon sintering process conditions is expressed mathematically. The authors suggest differentiating sintering modes to improve the sintered surface and the bulk of the product and dividing them into rough, semi-finishing, and finishing ones

The current status of orbital experiments for UHECR studies

Two types of orbital detectors of extreme energy cosmic rays are being developed nowadays: (i) TUS and KLYPVE with reflecting optical systems (mirrors) and (ii) JEM-EUSO with high-transmittance Fresnel lenses. They will cover much larger areas than existing ground-based arrays and almost uniformly monitor the celestial sphere. The TUS detector is the pioneering mission developed in SINP MSU in cooperation with several Russian and foreign institutions. It has relatively small field of view (+/-4.5 deg), which corresponds to a ground area of 6.4x10^3 sq.km. The telescope consists of a Fresnel-type mirror-concentrator (~2 sq.m) and a photo receiver (a matrix of 16x16 photomultiplier tubes). It is to be deployed on the Lomonosov satellite, and is currently at the final stage of preflight tests. Recently, SINP MSU began the KLYPVE project to be installed on board of the Russian segment of the ISS. The optical system of this detector contains a larger primary mirror (10 sq.m), which allows decreasing the energy threshold. The total effective field of view will be at least +/-14 degrees to exceed the annual exposure of the existing ground-based experiments. Several configurations of the detector are being currently considered. Finally, JEM-EUSO is a wide field of view (+/-30 deg) detector. The optics is composed of two curved double-sided Fresnel lenses with 2.65 m external diameter, a precision diffractive middle lens and a pupil. The ultraviolet photons are focused onto the focal surface, which consists of nearly 5000 multi-anode photomultipliers. It is developed by a large international collaboration. All three orbital detectors have multi-purpose character due to continuous monitoring of various atmospheric phenomena. The present status of development of the TUS and KLYPVE missions is reported, and a brief comparison of the projects with JEM-EUSO is given.Comment: 18 pages; based on the rapporteur talk given by M.I. Panasyuk at ECRS-2014; v2: a few minor language issues fixed thanks to the editor; to be published in the proceeding

ОРГАНИЗАЦИЯ РАДИАЦИОННОГО КОНТРОЛЯ НА ЭТАПАХ СТРОИТЕЛЬСТВА ОЛИМПИЙСКИХ ОБЪЕКТОВ В ГОРОДЕ-КУРОРТЕ СОЧИ

This paper presents data on the organization and results of the provision of the radiation safety in the period of preparation for the Winter Olympic and Paralympic games in Sochi, 2014. The following topics are overviewed in the paper: allocation of land plots for construction of the Olympic facilities; organization of the sanitary surveillance of the imported equipment, construction materials and designs for the construction of the Olympic facilities; putting the Olympic venues into operation. Dose rate of gamma radiation at all land plots, which were allocated for the construction of the Olympic facilities, conformed to the requirements of sanitary regulations. The average dose rate of gamma radiation was 0.11 μSv h-1 in the Coastal cluster and 0.14 μSv h-1 in the Mountain cluster. The radon fluence rate from the ground surface exceeded the prescribed limit of 80 mBq m-2 s-1 only at the land plot allocated for construction of the «House of receiving official delegations «Achipse» and the «House of receiving official delegations «Psekhako» in the Mountain cluster. The maximal value of 188 mBq m-2 s -1 was registered here. The buildings projects for this area included using radon protection measures, which were implemented during the construction.В работе представлены данные по организации и результатам обеспечения радиационной безопасности в период подготовки к зимним Олимпийским и Паралимпийским играм в Сочи-2014 при отводе земельных участков под строительство олимпийских объектов; организации санитарного надзора за ввозимым оборудованием, строительными материалами и конструкциями для строительства олимпийских объектов; вводе олимпийских объектов в эксплуатацию. По мощности дозы гамма-излучения все отведенные под строительство олимпийских объектов земельные участки соответствовали требованиям санитарных правил. Среднее значение мощности дозы гамма-излучения в Прибрежном кластере составило 0,11 мкЗв/ч, в Горном – 0,14 мкЗв/ч. Значения плотности потока радона с поверхности грунта только на одном участке, отведенном под строительство Дома приёма официальных гостей «Ачипсе» и Дома приёма официальных гостей «Псехако» в Горном кластере, превышали установленный норматив, составив 187,9 мБк/(м2.с), при нормативе 80 мБк/(м2.с). Для указанных зданий в проекте были предусмотрены, а при строительстве реализованы радонозащитные мероприятия. Удельная активность природных радионуклидов во всех исследованных пробах строительных материалов не превышала 370 Бк/кг, оборудование и конструкции для строительства, все сооружения и здания олимпийских объектов при вводе в эксплуатацию по радиологическим показателям соответствовали требованиям санитарных прави

Phase Composition and Microstructure of Ti-Nb Alloy Produced by Selective Laser Melting

The phase composition and microstructure of Ti-Nb alloy produced from composite titanium and niobium powder by selective laser melting (SLM) was studied. Produced monolayered Ti-Nb alloy enhanced the formation of fine-grained and medium-grained zones with homogeneous element composition of 36-38% Nb mass interval. Alloy phase composition responded to [beta]-alloy substrate phase (grain size was 5-7 pm) and non-equilibrium martensite [alpha]"- phase (grain size was 0.1-0.7 [mu]m). [alpha]"-phase grains were found along [beta]-phase grain boundaries and inside grains, including decreased niobium content. Alloy microhardness varied within 4200-5500 MPa

An extensive-air-shower-like event registered with the TUS orbital detector

TUS (Tracking Ultraviolet Set-up) is the world's first orbital detector of ultra-high-energy cosmic rays (UHECRs). It was launched into orbit on 28th April 2016 as a part of the scientific payload of the Lomonosov satellite. The main aim of the mission was to test the technique of measuring the ultraviolet fluorescence and Cherenkov radiation of extensive air showers generated by primary cosmic rays with energies above ~100 EeV in the Earth atmosphere from space. During its operation for 1.5 years, TUS registered almost 80,000 events with a few of them satisfying conditions anticipated for extensive air showers (EASs) initiated by UHECRs. Here we discuss an event registered on 3rd October 2016. The event was measured in perfect observation conditions as an ultraviolet track in the nocturnal atmosphere of the Earth, with the kinematics and the light curve similar to those expected from an EAS. A reconstruction of parameters of a primary particle gave the zenith angle around 44$^\circ$ but an extreme energy not compatible with the cosmic ray energy spectrum obtained with ground-based experiments. We discuss in details all conditions of registering the event, explain the reconstruction procedure and its limitations and comment on possible sources of the signal, both of anthropogenic and astrophysical origin. We believe this detection represents a significant milestone in the space-based observation of UHECRs because it proves the capability of an orbital telescope to detect light signals with the apparent motion and light shape similar to what are expected from EASs. This is important for the on-going development of the future missions KLYPVE-EUSO and POEMMA, aimed for studying UHECRs from space.Comment: 24 pages; v2: important changes to address comments by the anonymous referee; main conclusions unchange

НАУЧНОЕ ОБОСНОВАНИЕ МЕТОДИЧЕСКИХ ПОДХОДОВ К ОРГАНИЗАЦИИ И ПРОВЕДЕНИЮ ЗАКЛЮЧИТЕЛЬНОГО РАДИАЦИОННОГО ОБСЛЕДОВАНИЯ УЧАСТКОВ ТЕРРИТОРИИ, РЕАБИЛИТИРОВАННЫХ ПОСЛЕ ЗАГРЯЗНЕНИЯ ПРИРОДНЫМИ РАДИОНУКЛИДАМИ

According to the Federal target program “Provision of the nuclear and radiation safety in 2016-2020 and up to 2030”, activities on the liquidation of the nuclear legacy are performed in the Russian Federation. The nuclear legacy includes mines, pits, industrial facilities, burrows and tailings of the uranium processing facilities (objects of uranium legacy), objects of extraction and processing of precious and rare elements and mineral ore, producing the wastes with the increased concentration of natural radionuclides. Due to the damage or lack of the barriers, preventing the distribution of radionuclides, natural radionuclides contaminate the environment and expose the population residing in closely located communities. Radionuclides of radium ( 226Ra and 228Ra), radon (222Rn) and their daughter have the main contribution to the doses and corresponding radiation risks to the public residing in a vicinity of such facilities. According to the Russian legislative documents, exposure of the public residing in the area of location of the objects of the uranium legacy and objects and territories, contaminated by the natural radionuclides due to the past activities of the non-nuclear facilities is attributed to the natural exposure with the subsequent compliance to the requirements of NRB 99/2009 and OSPORB 99/2010 on limitations of natural exposure. The main direction of the use of the objects and territories contaminated by the natural radionuclides due to the past activities of nuclear and non-nuclear facilities is their unlimited use for the industrial purposes. The main criteria for the unlimited use of remediated areas and territories of buildings and constructions are the requirements of NRB-99/2009 and OSPORB-99/2010 for the construction of the residential and public buildings. The criteria of NRB-99/2009 and OSPORB 99/2010 for the industrial buildings would be applied for the use of the remediated areas and territories of buildings and constructions with the residual contamination by the natural radionuclides.  Российской Федерации в соответствии с Федеральной целевой программой «Обеспечение ядерной и радиационной безопасности на 2016–2020 годы и на период до 2030 года» проводятся работы по ликвидации ядерного наследия. К ядерному наследию относятся шахты, рудники, промышленные площадки заводов, отвалы и хвостохранилища урановых производств (объекты уранового наследия), а также объекты добычи и переработки драгоценных и редких элементов и минерального сырья, в результате деятельности которых образовались отходы с повышенным содержанием природных радионуклидов. Из-за разрушений или отсутствия барьеров, препятствующих распространению радионуклидов, происходит загрязнение природными радионуклидами объектов окружающей среды и облучение населения, проживающего в близлежащих населенных пунктах. Радионуклиды радия (226Ra и 228Ra) и их дочерние продукты распада вносят основной вклад в формирование дозы облучения и, соответственно, радиационных рисков для населения, проживающего вблизи таких объектов. В соответствии с отечественной нормативной базой, облучение населения, проживающего в районах размещения объектов уранового наследия, а также объектов и территорий, загрязненных природными радионуклидами в результате прошлой деятельности предприятий неядерных отраслей промышленности, относится к природному облучению, на него распространяются требования НРБ-99/2009 и ОСПОРБ-99/2010 по ограничению природного облучения. Направлениями использования объектов и территорий, загрязненных природными радионуклидами в результате прошлой деятельности предприятий ядерной и неядерных отраслей промышленности, после окончания мероприятий по их реабилитации будут являться неограниченное использование и использование в производственных целях. Для неограниченного использования реабилитированных участков территорий зданий и сооружений критериями будут являться требования НРБ-99/2009 и ОСПОРБ-99/2010 для строительства зданий жилищного и общественного назначения. Критериями использования реабилитированных участков территории зданий и сооружений с остаточным загрязнением природными радионуклидами в производственных целях будут являться требования НРБ-99/2009 и ОСПОРБ-99/2010 для строительства производственных зданий и сооружений.