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For over 100 years manned aviation has been based on pilots seeing and avoiding other aircraft. During this time aviation has evolved to a point where there were 37.4 million commercial flights scheduled in 2014 [1]. The national airspace system (NAS) of each country is a complex system-of-systems involving air traffic control, a network of navigation and communication facilities, airports, controlled and uncontrolled airspace, and the associated rules and regulations for each part of this system. It is into this system that we are now introducing unmanned aircraft systems (UAS) for commercial and civilian applications.

Energy production in a living cells is among the most important questions in biology and for the modern technology. Bacteriorhodopsin (bR) being a simplest tool to produce electric potential across membrane have received a lot of attention. It became one of the model membrane proteins, also because of its relative abundance in nature and relative ease of purification from natural source, H. salinarum. Unique properties of bR photocycle make it useful and promising in a wide variety of technical applications, thus giving rise to growing need of this protein. Despite the availability of the atomic structures there are still controversies in mechanism of proton pumping by bR. Homologous production of bR and its mutants in halobacteria is laborious, time-, and resource-consuming, therefore facile and robust E. coli expression system would be of wide interest. Recently several structures of GPCRs were obtained using GPCR-lysozyme fusion protein where lysozyme served as a crystallization tag. We suppose that bR would be a good model for investigation of versatility of lysozyme as crystallization tags. As in meso grown crystals of bR are prone to twinning crystallization of bR-lysozyme fusion protein could provide twinning-free crystals allowing to clarify the details of bR photocycle. In this work, it was suggested that the low yield of bR expression in E. coli can be attributed to the poor insertion of the protein into membrane. We have introduced protein complementary approach that may allow to localize the problem in membrane protein expression using finite number of steps. It is based on constructing of chimeric proteins between a protein of interest and complementary homologous protein expressed with high yield. Applying this approach we showed that the substitution of first ten amino acids of bR for the corresponding eight amino acids from SRII increase the expression yield of bR more than 50-fold. The reason for high yield of the chimera could be the positively charged Arg7 on the N-terminus of bR that deviates from “positive inside” rule and absent in the chimera. We expressed bR mutants R7Q and R7E where this positive charge was substituted for neutral and negative charges, respectively. Although the yields of the mutants were higher than of wild type gene, they were still considerably lower than yield of chimera. Thus, the positive charge on the N-terminus of bR is not the reason of its poor expression in E. coli. A putative stem structure 5'-end of bR mRNA was proposed to be another reason of low bR expression in E. coli. The expression yield of optimized wild type bR gene was on the same level as yield of the chimera. Therefore, the low yield of bacteriorhodopsin native gene in E. coli was attributed to the unfavorable mRNA structure of native gene close to the ribosome binding site. When purified under non-denaturing conditions, the protein have retained its functionality. The yield of functional homogenious protein was 2.4±1.3 mg per liter of culture what is sufficient for a large-scale crystallization and industrial use. Using this approach we produced as well functional V49A, D85N, and D96N mutants of bR in short time with yields of 0.3, 3.8, and 8.8 mg per liter of culture, respectively. We suppose that increased yield of D85N and D96N mutants can be explained by better incorporation of positively charged C-helix of bR into E. coli membrane. The second goal, crystallization of the bR-lysozyme fusion protein, demands a high yield expression system and effective crystallization approaches. Here, bR can serve as a reference. High resolution structures show that bR trimers are surrounded by the belt of native lipid. Despite multiple protocols of E. coli expression, 3D crystallization of this protein was not reported. Since expressed in E. coli bR-lysozyme fusion protein would not have H. salinarum lipids bound and purification of this protein is based on the application of DDM instead of usual OG, careful investigation of the influence of lipid/detergent environment on in meso crystallization is important. To study the influence of detergent on the in meso crystallization we set large-scale crystallization trials with homologously expressed bR in mixtures of detergents. The crystals of different size (up to 300 μm) were obtained. Three crystals grown in mixtures of detergents radiation gave at synchrotron a diffraction up to 1.45 Å. The full datasets were collected and three structures of bR were solved. We have not observed detergent molecules on the electron densities corresponding to the structures. These experiments showed that detergent molecules do not participate in the formation of the crystal lattice of bR. Moreover, there is no need to exchange the detergent from DDM used for purification to OG that is generally used for in meso crystallization of homologously expressed bR. Then, using the protein expressed E. coli the crystals of wild type bR and D85N and D96N bR mutants were grown. Crystals were tested under synchrotron radiation and gave a diffraction up to 2.5Å resolution. The first 3D crystals of bR expressed in E. coli demonstrate that expression of bR and its mutants in E. coli is suitable for scientific and industrial applications. In addition, the successful crystallization of protein isolated from E. coli demonstrated that H. salinarum lipids are not strictly required for grow of well ordered bR crystals. Using the optimized bR gene we have expressed bR-lysozyme fusion proteins in E. coli with yield up to 0.9 mg of functional protein per liter of culture. This protein was purified under non-denaturing conditions to homogeneity and in meso crystallization trials are ongoing.

International audience; Heterologous overexpression of functional membrane proteins is a major bottleneck of structural biology. Bacteriorhodopsin from Halobium salinarum (bR) is a striking example of the difficulties in membrane protein overexpression. We suggest a general approach with a finite number of steps which allows one to localize the underlying problem of poor expression of a membrane protein using bR as an example. Our approach is based on constructing chimeric proteins comprising parts of a protein of interest and complementary parts of a homologous protein demonstrating advantageous expression. This complementary protein approach allowed us to increase bR expression by two orders of magnitude through the introduction of two silent mutations into bR coding DNA. For the first time the high quality crystals of bR expressed in E. Coli were obtained using the produced protein. The crystals obtained with in meso nanovolume crystallization diffracted to 1.67 Å.

The development of global navigation satellite systems (GNSS) provides a solution of many applied problems with increasingly higher quality and accuracy nowadays. Researches that are carried out by the Bavarian Academy of Sciences and Humanities in Munich (BAW) in the field of airborne gravimetry are based on sophisticated data processing from high frequency GNSS receiver for kinematic aircraft positioning. Applied algorithms for inertial acceleration determination are based on the high sampling rate (50Hz) and on reducing of such factors as ionosphere scintillation and multipath at aircraft /antenna near field effects. The quality of the GNSS derived kinematic height are studied also by intercomparison with lift height variations collected by a precise high sampling rate vertical scale [1]. This work is aimed at the ways of more accurate determination of mini-aircraft altitude by means of high frequency GNSS receivers, in particular by considering their dynamic behaviour.

В статье представлено развитие принципа построения автоматической пилотажно-навигационной системы (АПНС) для беспилотного летательного аппарата (БЛА). Принцип заключается в синтезе комплексных систем управления БПЛА не только на основе использования алгоритмов БИНС, но и алгоритмов, объединяющих в себе решение задач формирования и отработки сформированной траектории резервированной системой управления и навигации. Приведены результаты аналитического исследования и данные летных экспериментов разработанных алгоритмов АПНС БЛА, обеспечивающих дополнительное резервирование алгоритмов навигации и наделяющих БЛА новым функциональной способностью по выходу в заданную точку пространства с заданной скоростью в заданный момент времени с учетом атмосферных ветровых возмущений. Предложена и испытана методика идентификации параметров воздушной атмосферы: направления и скорости W ветра. Данные летных испытаний полученного решения задачи терминальной навигации демонстрируют устойчивую работу синтезированных алгоритмов управления в различных метеоусловиях. The article presents a progress in principle of development of automatic navigation management system (ANMS) for small unmanned aerial vehicle (UAV). The principle defines a development of integrated control systems for UAV based on tight coupling of strap down inertial navigation system algorithms and algorithms of redundant flight management system to form and control flight trajectory. The results of the research and flight testing of the developed ANMS UAV algorithms are presented. The system demonstrates advanced functional redundancy of UAV guidance. The system enables new UAV capability to perform autonomous multidimensional navigation along waypoints with controlled speed and time of arrival taking into account wind. The paper describes the technique for real-time identification of atmosphere parameters such as wind direction and wind speed. The flight test results demonstrate robustness of the algorithms in diverse meteorological conditions.

Современный этап развития комплексов автоматического управления и навигации малогабаритными БЛА многократного применения предъявляет высокие требования к автономности, точности и миниатюрности данных систем. Противоречивость требований диктует использование функционального и алгоритмического объединения нескольких разнотипных источников навигационной информации в едином вычислительном процессе на основе методов оптимальной фильтрации. Получили широкое развитие бесплатформенные инерциальные навигационные системы (БИНС) на основе комплексирования данных микромеханических датчиков инерциальной информации и датчиков параметров движения в воздушном потоке с данными спутниковых навигационных систем (СНС). Однако в современных условиях такой подход не в полной мере реализует требования к помехозащищённости, автономности и точности получаемой навигационной информации. Одновременно с этим достигли значительного прогресса навигационные системы, использующие принципы корреляционно экстремальной навигации по оптическим ориентирам и цифровым картам местности. Предлагается схема построения автономной автоматической навигационной системы (АНС) для БЛА многоразового применения на основе объединения алгоритмов БИНС, спутниковой навигационной системы и оптической навигационной системы. The modern stage of automatic control and guidance systems development for small unmanned aerial vehicles (UAV) is determined by advanced requirements for autonomy, accuracy and size of the systems. The contradictory of the requirements dictates novel functional and algorithmic tight coupling of several different onboard sensors into one computational process, which is based on methods of optimal filtering. Nowadays, data fusion of micro-electro mechanical sensors of inertial measurement units, barometric pressure sensors, and signals of global navigation satellite systems (GNSS) receivers is widely used in numerous strap down inertial navigation systems (INS). However, the systems do not fully comply with such requirements as jamming immunity, fault tolerance, autonomy, and accuracy of navigation. At the same time, the significant progress has been recently demonstrated by the navigation systems, which use the correlation extremal principle applied for optical data flow and digital maps. This article proposes a new architecture of automatic navigation management system (ANMS) for small UAV, which combines algorithms of strap down INS, satellite navigation and optical navigation system.

Science advances 5(4), eaav2671 (2019). doi:10.1126/sciadv.aav2671, Published by American Association for the Advancement of Science, Washington, DC [u.a.]