bluuebunny/crossref_metadata_2025 huggingface dataset:
Non‐deterministic optimal power flow considering the uncertainties of wind power and load demand by multi‐objective information gap decision theory and directed search domain method
Authors: Rahmani Shima , Amjady Nima
Published: July 2018

Optimal power flow (OPF) as an important operation function of wind power‐integrated power systems encounters the uncertainties of load demand and wind power. To cope with these uncertainty sources, various OPF models including deterministic OPF, probabilistic OPF, scenario‐based OPF, stochastic OPF, robust OPF and recently information gap decision theory (IGDT)‐based OPF have been presented in the literature. A multi‐objective IGDT‐based AC OPF model is presented which can simultaneously optimise various uncertainty horizons pertaining to load demands and wind powers considering the specified robustness level. Another main contribution of this study is presenting an effective directed search domain (DSD)‐based multi‐objective solution method to solve the proposed multi‐objective IGDT‐based AC OPF problem. The proposed OPF model and solution approach are tested on the IEEE 118‐bus test system and the obtained results are compared with the results of other OPF models and solution methods. These comparisons illustrate the effectiveness of the proposed multi‐objective IGDT‐based AC OPF model as well as the proposed DSD‐based multi‐objective solution method.
SSOs caused by OLMOC in a power system with the PMSGs for wind power generation
Authors: Du Wenjuan , Chen Xiao , Wang Haifeng
Published: July 2018

The authors study the modal condition, under which the sub‐synchronous oscillations (SSOs) may be caused by the grid integration of a permanent magnet synchronous generator (PMSG) in a power system. The study is conducted by using a closed‐loop interconnected model of the power system with the PMSG, which consists of a PMSG subsystem and a subsystem of the remainder of power system (ROPS). The modal condition is the nearness of an SSO mode of open‐loop PMSG subsystem to an SSO mode of open‐loop ROPS subsystem on the complex plane. It is named as the open‐loop modal coupling (OLMOC). The study shows that when the OLMOC takes place, strong sub‐synchronous interactions (SSIs) are induced by the PMSG and may very likely decrease the damping of SSOs in the power system. A formula to approximately evaluate the degree of damping decrease caused by the OLMOC is derived in this study. Hence, the mechanism of why the PMSG may jeopardize power system stability is revealed from the viewpoint of open‐loop modal condition. Study cases are displayed to confirm the analytical investigation. They indicate that the growing torsional SSOs and the SSIs between the PMSGs take place when the OLMOC occurs.
Experimental investigation of the effects of sonication time and volume concentration on the performance of PVT solar collector
Authors: Rajendiran Gangadevi , Kuppusamy Vinayagam Babu , Shanmugasundaram Senthilraja
Published: July 2018

In this research, the effects of sonication time and volume concentration of cupric oxide (CuO)/water nanofluids on the thermal conductivity, viscosity and performance of photovoltaic–thermal (PVT) solar collector are investigated experimentally. Pure water, 0.05, 0.1 and 0.2% volume concentrations of CuO/water nanofluids prepared with 1, 2, 3 and 4 h sonication time are used as the heat transfer fluids in this study. The experimental results show that the thermal conductivity and viscosity of nanofluids are the functions of sonication time and volume concentration and using a 0.2 vol.% nanofluid prepared with 4 h sonication time, the thermal conductivity and viscosity were enhanced up to 3.5 and 7.5%, respectively, with respect to the base fluid, whereas for the same volume concentration and sonication time, the observed thermal and electrical efficiencies of the PVT solar collector are 80.7 and 15.1%, respectively, at 12 noon. It was observed that the highest total efficiency of the PVT solar collector of about 95.8% was obtained for 0.2% CuO/water nanofluid and 4 h sonication time at 12 noon.
Coordinated control of parallel operated renewable‐energy‐based DG systems
Authors: Chilipi Rajasekharareddy , Alsayari Naji , El Aroudi Abdelali
Published: July 2018

This study proposes a coordinated control algorithm for two parallel‐operated distributed generation (DG) systems fed from different renewable energy sources. The control algorithm ensures accurate control of reference active power generation from the inverters in the DG systems. In addition to reference power generation, the control algorithm also offers compensation of harmonics and reactive currents of the local loads by utilising the remaining capacities of the inverters in the DG systems. For this purpose, the control algorithm estimates compensating factors for each inverter based on the distributed harmonic and reactive currents. The inverter with a higher surplus capacity contributes to higher compensation and vice versa. The harmonic and reactive currents of the load are extracted using least mean mixed‐norm adaptive algorithm for effective compensation. Furthermore, the control algorithm automatically switches to low‐voltage ride through (LVRT) on sensing the grid faults. During LVRT, the active power generation by the inverters in DG systems is reduced and reactive currents are injected to support the grid recovery. The proposed control scheme is thoroughly investigated using computer simulations and hardware‐in‐the‐loop‐based experiments to show its feasibility and effectiveness.
Simultaneous optimisation of photovoltaic hosting capacity and energy loss of radial distribution networks with open unified power quality conditioner allocation
Authors: Lakshmi Shubh , Ganguly Sanjib
Published: July 2018

This study presents a multi‐objective planning approach to optimally place open unified power quality conditioner (UPQC‐O) by simultaneously optimising the photovoltaic (PV) hosting capacity (PVHC) and energy loss of distribution networks. The modelling of UPQC‐O consisting of a series and a shunt inverter is carried out so as to place in distribution networks. The Pareto‐dominance‐based approach is used to simultaneously optimise the objective functions to determine the optimal PV generation capacity in each bus and the locations of the inverters of UPQC‐O. The limits on bus voltage magnitude, line current flow, maximum PV generation capacity in each bus, and the percentage of voltage sag mitigated load are considered to be the operational constraints in this planning problem. The solution strategy used is the multi‐objective particle swarm optimisation. The approach provides the Pareto‐approximation set consisting of a number of trade‐off solutions in view of PVHC and energy loss. A utility can choose a solution for implementation depending on its desired PVHC and/or energy loss level. The results show that the PV deployment in distribution networks reduces the energy loss. However, the amount of energy loss reduction diminishes with higher and higher values of PV capacity integration.
Extragalactic radio source stability and VLBI celestial reference frame: insights from the Allan standard deviation
Authors: Gattano C. , Lambert S. B. , Le Bail K.
Published: July 2018

Aims. We investigate the composition of the noise in coordinate time series of several hundreds of extragalactic radio sources monitored by the geodetic VLBI program since 1979. The noise type is identified at all available timescales longer than one year, following the observational history of the source.

Methods. We computed the Allan standard deviation of coordinate time series and developed a Monte Carlo test to evaluate the influence of the irregular sampling and error on data onto the noise type identification. We classified the radio sources into three categories depending on their type of noise and taking into account the dominating noise at different timescales: from the category AV0, which contains sources with a stable behavior at all timescales, to the category AV2, which contains sources whose coordinates are dominated by random walks at the longest timescales.

Results. We found that almost no source exhibited “idealized” white noise. Only 5% of the 647 sources we studied belong to the category AV0 (stable sources). Moreover, we found that this class contains sources with relatively short observational histories, suggesting that after some years, a source whose astrometric position has shown a stable behavior is likely to become unstable. This questions the existence of the stable source paradigm and adds complementary information in the crucial task of selecting sources on which to base the axes of the celestial reference frame.
H2chemistry in interstellar ices: the case of CO ice hydrogenation in UV irradiated CO:H2ice mixtures
Authors: Chuang K.-J. , Fedoseev G. , Qasim D. , Ioppolo S. , van Dishoeck E. F. , Linnartz H.
Published: July 2018

Context.In dense clouds, hydrogenation reactions on icy dust grains are key in the formation of molecules, like formaldehyde, methanol, and complex organic molecules (COMs). These species form through the sequential hydrogenation of CO ice. Although molecular hydrogen (H2) abundances can be four orders of magnitude higher than those of free H-atoms in dense clouds, H2surface chemistry has been largely ignored; several laboratory studies show that H2does not actively participate in “non-energetic” ice chemistry because of the high activation energies required.

Aims.For the example of CO ice hydrogenation, we experimentally investigated the potential role of H2molecules on the surface chemistry when energetic processing (i.e., UV photolysis) is involved. We test whether additional hydrogenation pathways become available upon UV irradiation of a CO:H2ice mixture and whether this reaction mechanism also applies to other chemical systems.

Methods.Ultra-high vacuum (UHV) experiments were performed at 8–20 K. A pre-deposited solid mixture of CO:H2was irradiated with UV-photons. Reflection absorption infrared spectroscopy (RAIRS) was used as an in situ diagnostic tool. Single reaction steps and possible isotopic effects were studied by comparing results from CO:H2and CO:D2ice mixtures.

Results.After UV-irradiation of a CO:H2ice mixture, two photon-induced products, HCO and H2CO, are unambiguously detected. The proposed reaction mechanism involves electronically excited CO in the following reaction steps: CO + hν→CO*, CO*+ H2→HCO + H where newly formed H-atoms are then available for further hydrogenation reactions. The HCO formation yields have a strong temperature dependence for the investigated regime, which is most likely linked to the H2sticking coefficient. Moreover, the derived formation cross section reflects a cumulative reaction rate that mainly determined by both the H-atom diffusion rate and initial concentration of H2at 8–20 K and that is largely determined by the H2sticking coefficient. Finally, the astronomical relevance of this photo-induced reaction channel is discussed.
Gaia DR2 reveals a very massive runaway star ejected from R136
Authors: Lennon D. J. , Evans C. J. , van der Marel R. P. , Anderson J. , Platais I. , Herrero A. , de Mink S. E. , Sana H. , Sabbi E. , Bedin L. R. , Crowther P. A. , Langer N. , Ramos Lerate M. , del Pino A. , Renzo M. , Simón-Díaz S. , Schneider F. R. N.
Published: July 2018

A previous spectroscopic study identified the very massive O2 III star VFTS 16 in the Tarantula Nebula as a runaway star based on its peculiar line-of-sight velocity. We use the Gaia DR2 catalog to measure the relative proper motion of VFTS 16 and nearby bright stars to test if this star might have been ejected from the central cluster, R136, via dynamical ejection. We find that the position angle and magnitude of the relative proper motion (0.338±0.046 mas yr−1, or approximately 80±11 km s−1) of VFTS 16 are consistent with ejection from R136 approximately 1.5±0.2 Myr ago, very soon after the cluster was formed. There is some tension with the presumed age of VFTS 16 that, from published stellar parameters, cannot be greater than 0.9+0.3−0.2 Myr. Older ages for this star would appear to be prohibited due to the absence of He I lines in its optical spectrum, since this sets a firm lower limit on its effective temperature. The dynamical constraints may imply an unusual evolutionary history for this object, perhaps indicating it is a merger product. Gaia DR2 also confirms that another very massive star in the Tarantula Nebula, VFTS 72 (alias BI 253; O2 III-V(n)((f*)), is also a runaway on the basis of its proper motion as measured by Gaia. While its tangential proper motion (0.392±0.062 mas yr−1 or 93±15 km s−1) would be consistent with dynamical ejection from R136 approximately 1 Myr ago, its position angle is discrepant with this direction at the 2σ level. From their Gaia DR2 proper motions we conclude that the two ∼100 M⊙ O2 stars, VFTS 16 and VFTS 72, are fast runaway stars, with space velocities of around 100 km s−1 relative to R136 and the local massive star population. The dynamics of VFTS 16 are consistent with it having been ejected from R136, and this star therefore sets a robust lower limit on the age of the central cluster of ∼1.3 Myr.
Detection of the gravitational redshift in the orbit of the star S2 near the Galactic centre massive black hole
Authors:   GRAVITY Collaboration, Abuter R. , Amorim A. , Anugu N. , Bauböck M. , Benisty M. , Berger J. P. , Blind N. , Bonnet H. , Brandner W. , Buron A. , Collin C. , Chapron F. , Clénet Y. , dCoudé u Foresto V. , de Zeeuw P. T. , Deen C. , Delplancke-Ströbele F. , Dembet R. , Dexter J. , Duvert G. , Eckart A. , Eisenhauer F. , Finger G. , Förster Schreiber N. M. , Fédou P. , Garcia P. , Garcia Lopez R. , Gao F. , Gendron E. , Genzel R. , Gillessen S. , Gordo P. , Habibi M. , Haubois X. , Haug M. , Haußmann F. , Henning Th. , Hippler S. , Horrobin M. , Hubert Z. , Hubin N. , Jimenez Rosales A. , Jochum L. , Jocou L. , Kaufer A. , Kellner S. , Kendrew S. , Kervella P. , Kok Y. , Kulas M. , Lacour S. , Lapeyrère V. , Lazareff B. , Le Bouquin J.-B. , Léna P. , Lippa M. , Lenzen R. , Mérand A. , Müler E. , Neumann U. , Ott T. , Palanca L. , Paumard T. , Pasquini L. , Perraut K. , Perrin G. , Pfuhl O. , Plewa P. M. , Rabien S. , Ramírez A. , Ramos J. , Rau C. , Rodríguez-Coira G. , Rohloff R.-R. , Rousset G. , Sanchez-Bermudez J. , Scheithauer S. , Schöller M. , Schuler N. , Spyromilio J. , Straub O. , Straubmeier C. , Sturm E. , Tacconi L. J. , Tristram K. R. W. , Vincent F. , von Fellenberg S. , Wank I. , Waisberg I. , Widmann F. , Wieprecht E. , Wiest M. , Wiezorrek E. , Woillez J. , Yazici S. , Ziegler D. , Zins G.
Published: July 2018

The highly elliptical, 16-year-period orbit of the star S2 around the massive black hole candidate Sgr A✻ is a sensitive probe of the gravitational field in the Galactic centre. Near pericentre at 120 AU ≈ 1400 Schwarzschild radii, the star has an orbital speed of ≈7650 km s−1, such that the first-order effects of Special and General Relativity have now become detectable with current capabilities. Over the past 26 years, we have monitored the radial velocity and motion on the sky of S2, mainly with the SINFONI and NACO adaptive optics instruments on the ESO Very Large Telescope, and since 2016 and leading up to the pericentre approach in May 2018, with the four-telescope interferometric beam-combiner instrument GRAVITY. From data up to and including pericentre, we robustly detect the combined gravitational redshift and relativistic transverse Doppler effect for S2 of z = Δλ / λ ≈ 200 km s−1/c with different statistical analysis methods. When parameterising the post-Newtonian contribution from these effects by a factor f , with f = 0 and f = 1 corresponding to the Newtonian and general relativistic limits, respectively, we find from posterior fitting with different weighting schemes f = 0.90 ± 0.09|stat ± 0.15|sys. The S2 data are inconsistent with pure Newtonian dynamics.
Global Existence of the Three Dimensional Heat-conductive Incompressible Viscous Fluids
Authors: Wu Jie
Published: July 2018

In this paper, we consider the Cauchy problem of non-stationary motion of heatconducting incompressible viscous fluids in ℝ3. About the heat-conducting incompressible viscous fluids, there are many mathematical researchers study the variants systems when the viscosity and heat-conductivity coefficient are positive. For the heat-conductive system, it is difficulty to get the better regularity due to the gradient of velocity of fluid own the higher order term. It is hard to control it. In order to get its global solutions, we must obtain the a priori estimates at first, then using fixed point theorem, it need the mapping is contracted. We can get a local solution, then applying the criteria extension. We can extend the local solution to the global solutions. For the two dimensional case, the Gagliardo-Nirenberg interpolation inequality makes use of better than the three dimensional situation. Thus, our problem will become more difficulty to handle. In this paper, we assume the coefficient of viscosity is a constant and the coefficient of heat-conductivity satisfying some suitable conditions. We show that the Cauchy problem has a global-in-time strong solution (u,θ) on ℝ3 ×(0, ∞).
Numerical Simulation of Nozzle Flow Field with Secondary Injection Thrust Vector Control
Authors: Noaman H.R. , Bin Tang Hai , Khalil Elsayed
Published: July 2018

Numerical simulations are performed to characterize the secondary injection thrust vector control. For this objective the following measurements were taken: considering the flow to be compressible and turbulent using Realizable k-ε turbulence model accompanied by enhanced wall treatment, the comparison between the CFD results and the experimental results shows a very good agreement. Then a parametric study on injection mass flow rate (changing secondary stagnation pressure) with the same injection location and injection angle is done. The results stated that increasing the injectant mass flow rate lead to shock impingement from opposite wall at secondary stagnation pressure 1.4 of the primary stagnation pressure.
Battery group parameter selection and dynamic simulation of pure electric vehicle
Authors: Minrui Guo , Lei Cheng
Published: July 2018

The battery pack is one of the core components of pure electric vehicle, dynamic performance of the whole vehicle is closely related to the matching design of the battery, and is affected by the air resistance coefficient and the windward area of the whole vehicle. The dynamic indicators include maximum driving speed, 0-100km/h acceleration time and climbing grade, the battery parameters are designed and matched before the vehicle design, mainly analyze influence on the vehicle dynamic performance of the types of batteries, air resistance coefficient, windward area by the simulation software ADVISOR, and optimize the combination of these parameters. The results show that the dynamic performance of the vehicle reaches the initial design index and the dynamic performance of the vehicle is improved significantly.
Effect of Ellipsoidal Modulus and Internal Pressure on Bearing Capacity of Thrust-Bearing Aft Dome
Authors: Peng Wang , Ruixiang Fan , Cheng Huang , Dongyang Yan , Feifan Wang
Published: July 2018

In order to analyse the effect of ellipsoidal modulus and internal pressure on bearing capacity of thrust-bearing aft dome, we obtain the stress and strain distribution and bearing capacity of 1.6, 1.4 and 1.0 modulus ellipsoidal aft dome under 0MPa~0.98MPa internal pressure and engine thrust by finite element method. We find as the modulus decreases, the bearing capacity of the ellipsoidal aft dome increases, and as internal pressure decreases, within the engineering range (0~0.98MPa), the bearing capacity increases. The conclusion can provide a guidance for the design of thrust-bearing aft dome.
Effects of Airflow Deflection Angle in Diffuser on Forced Response Caused by Impeller-diffuser Interaction in Centrifugal Compressors
Authors: Peng Sun , Yanrong Wang , Xiaobo Zhang
Published: July 2018

Aeroelasticity has always been a significant issue of compressors. Impeller-diffuser interaction (IDI) produces periodic aerodynamic excitation which forces the blades to vibrate in centrifugal compressors, and eventually causes the damage of blades. Therefore, it is of great importance to investigate the IDI in centrifugal compressors and the effects on the vibration of blades. In this paper, it is discussed in detail that the deflection angle of the airflow in diffuser affects the IDI of the centrifugal compressor and the vibration of blades. The results show that if deflection angle is positive, the interaction of the diffuser on impeller and the vibration of main blades are decreased. However, on condition that the deflection angle is excessive, the interaction of the diffuser on the flow field of impeller will be intensified, and the vibration of the main blades will be stronger. Therefore, it is necessary to reasonably control the range of the deflection angle so that centrifugal compressors are able to work in a safer environment.
Research on Interactive Routing of Cable in Virtual Environment
Authors: WAN Bi-le , HE Wen-xing , CHEN Chang-yu
Published: July 2018

On the basis of analyzing the defects of existing design methods of cable wiring, the feasibility of interactive cabling design in virtual environment is pointed out. Based on the discrete control point, the geometric shape modeling method and the topological structure matrix modeling method based on the wire unit are presented. Adopt the method of real-time interactive cable modeling and wiring, explains the wiring process and control point positioning technology, and through the stratified multistage collision interference detection technology improve the authenticity of the wiring process and results. After the wiring design is completed, the statistical summary of the model information is compiled to generate various inventory reports to guide the actual production.
Study on the Mechanism of a Carrier-based Engine Parts' Performance Decline and Its Impact on the Whole Engine Performance
Authors: Heng Wu , Benwei Li , Shufan Zhao , Yonghua Wang
Published: July 2018

The technical approach "use – parts' change - engine performance change" has been adopted to study and analyse the gas unit parts' performance changes of an engine after a long time operation. The mechanism of performance decline of the turbine is analysed based on the numerical simulation, the impact of components' performance decline on overall engine performance is studied and the correlation analysis is carried out. The results show that the change of turbine tip clearance, roughness increase and surface change will lead to the enhancement of secondary flow and the increase of influence area, and the turbulence effect is strengthened, resulting in the decrease of turbine circulation capacity and efficiency. The booster ratio of high pressure compressor, the flow capacity of high pressure and low pressure turbines, the flow capacity and efficiency of fan are the major component parameters causing the overall engine performance's degradation. And it also provides theoretical basis for the prevention of engine performance's degradation and online washing of parts and the whole machine.
Thermal Cycling Toughness and Strength Estimation of Cryogenic Filled Tank
Authors: Uglanov Dmitry , Sarmin Dmitry , Akulova Alina , Aksenova Daria , Panshin Roman
Published: July 2018

At present, technologies based on liquid natural gas (LNG) using start to find a wide use. They also demand technologies of working fluid storage and transportation in cryogenic liquid condition. The working fluid will be used after its regasification from cryogenic liquid condition. When the gas cylinder is filled with gas, there is a danger of exceeding the temperature stresses in the cylinder walls. For the study, there is a method for calculating unsteady thermal conductivity for studying the temperature stresses in the wall of a gas cylinder during its interaction with an evaporating cryogen. This method is used for determining the thermoelastic stresses of the cryogenic filled tank. The CAE- calculation of the strength of the cryogenic filled tank is also done.
A Specific Sliding Mode Control for Autopilot Design of Bank-to-Turn Missiles
Authors: Huai Zepeng , Wang Hongbo , Gong Min , Ren Pengfei , Xu Zijian , Cheng Lingxiao
Published: July 2018

This paper studies the BTT missile's sliding mode flight controller. Firstly, the control model is established according to dynamic inverse method and the general dynamic equation of the missile flying in the atmosphere. Then, the sliding mode controller is designed and it adopts the time-varying sliding mode surface, the self-defined reaching law and the adaptive control parameters. Finally, three sets of simulation are carried out to prove the flight controller designed in this paper for BTT missile can follow the guidance instructions and meet operational needs.
Increasing the Energy Efficiency of the Power Supply System on Liquefied Natural Gas through the Use of a Combined Cycle Gas Turbine Plant
Authors: Zaika S V , Uglanov D A , Shatokhin E A , Zaika S S , Shimanov A A
Published: July 2018

The use of LNG for the production of additional energy is topical today. Very often LNG is used for gasification of settlements and industrial enterprises. LNG makes it possible to gasify objects remote from main pipelines for long distances by creating an LNG reserve directly from the consumer, avoiding the construction of expensive piping systems. However, in this case, there are large losses of cryoproduct and its low-potential heat. In this article, we propose a technical solution for compensating for the loss of cryoproducts during storage using an installation consisting of two circuits, one of which is a loss compensation loop and the other is a circuit for generating additional energy. The conducted researches showed that the use of this system allowed to return the previously used for liquefying electric power in the amount of 24%.
Hertz Model Based Contact Modeling for Joints with Clearance
Authors: Wang Jielong , Shi Bing
Published: July 2018

This paper presents the techniques of contact modeling for revolute joints in flexible multibody systems, in which the dry clearance revolute joints have been coupled with the flexibility of connected bodies. The contact model for revolute joints takes into account the relative planar motion caused by the clearance between the outer and inner races. This model applies a penalty method to simulate the phenomenon of inner-penetration between contact/impact bodies. The relationship between the normal contact force and the inner-penetration is described by the nonlinear Hertz model with energy dissipation. Meanwhile, the friction force can be predicted from continuous Coulomb's law. Finally, an example of flexible multibody systems has been simulated by using the developed contact models.
The IR Characteristics Modeling and Simulation of the HEO Target
Authors: Dongxing Tao , Boying Lin , Peng Du , Yanqiang Bi , Yonghong Shang , Xiyuan Li , Jing Wang
Published: July 2018

Space target infrared (IR) characteristics model can be used to design space target detection sensor, generating simulation data to validate the data processing algorithms, such as target detection and tracking. In the work, a HEO target IR characteristics model is built. The model consists of the geometry module and the IR radiometric module. Unlike the traditional space IR model, the temperature of cabin inner is used as the simulation origin. Using the model, the irradiance spectra of HEO target are calculated for different target temperature. With the calculation results, the main wavelength range for HEO detection is analyzed. Using the equvalent temperature, the work also designs a simulative target, which has the similar IR characteristics of a HEO target. The simulator can be used in the ground test for the imaging sensor or target decoy.
Research on Hot-Wire Low Pressure Wind Speed Measurement System
Authors: Xiaofang Yin , Xiyuan Li , Qinghua Gao , Jing Wang
Published: July 2018

In order to verify the correctness of the thermal control design, the Mars rover needs to conduct a thermal test on the ground during the construction of the Mars exploration mission. In the course of the thermal test, real-time measurement of the wind speed at low pressure is required. Therefore, it is needed to establish a low-pressure wind speed measurement system. This article describes the composition of the test system, the choice of measurement sensors, in which the impact of wire resistance, electromagnetic interference and other factors are taken into account, and the design of the test process is completed.
Cutting force analysis in machining of titanium alloy with solid carbide cutters of different geometriy
Authors: Jianyong Liu , Lihong Qiao , Wuyi Chen
Published: July 2018

In order to study the cutting force in machining of titanium alloy with solid carbide cutters of different geometriy, variable helix (VH), variable pitch (VP) and standard (SD) milling cutter were used to machine titanium alloy TB6 via dry milling. The influence of cutting parameters and geometric structure parameters of milling cutters on the cutting force was investigated by the analysis of radial and tangential forces in the cutting process with three kinds of milling cutters. The experiment results showed that cutting parameters had the same influence on the radial force and tangential force of the three milling cutters, and the influence of geometric structure parameters on radial force and tangential force was different. Compared with the SD milling cutter, the change of pitch and helix resulted in the increase of radial and tangential forces, the pitch change led to the radial force being larger than the tangential force, and the helix change led to the radial force being smaller than the tangential force.
The Vortex Aircooler System for Cutting Materials in Aerospace Industry
Authors: Belov G.O. , Dostovalova S.S , Barbonov E. О. , Uglanov D.A. , Chertykovtsev P.A. , Panshin R.A.
Published: July 2018

In aerospace industry there is a situation, when it is not possible to use liquid cooling of cutting zone, because we have special material or special construction. How often in that case used air fluent, but it has some problems with life cycle tools, quality and cutting time. For solving these problems was use the vortex effect, it was open less than one hundred years ago. The unit for making vortex effect is could vortex tube. It was done the design the vortex tube of air cooler system for cutting using some researching [1-5]. Some experimental dates gave verification. The construction was made by metal materials and now is using on JSC «Salut», Samara..
A Fixed Wing UAV Path Planning Algorithm Based On Genetic Algorithm and Dubins Curve Theory
Authors: Yan Peng , Yan Zhuo , Zheng Hongxing , Guo Jifeng
Published: July 2018

Path planning is an essential problem in the autonomy research of UAVs. This paper proposes a new path planning algorithm for fixed wing UAVs based on genetic algorithm (GA) and Dubins curve theory. Path planning is treated as a global optimization problem under certain constraints, including the velocity vectors of initial and goal points and the minimum turning radius of UAVs. Dubins curve theory is utilized to satisfy the velocity vector constraints. GA is utilized to generate the shortest threats avoidance path in a 2D environment. A new encoding scheme is proposed, taking into account initial circles, goal circles, threats circles and the positional relationship between the path and these circles. The 2D Dubins path is converted to Dubins airplane path by adding a flight-path angle to it. The algorithm was tested in a complex flight environment and the planned path was tracked by a 6DOF Simulink model of a fixed wing UAV. Results show that the algorithm can generate shortest threats avoidance path in a complicated 3D environment and meanwhile satisfy constraints mentioned above.
Research on Interior Ballistic of a Gas Multi-stage Cylinder Ejection
Authors: Huang Mei , Jiang Yi , Wang Boman
Published: July 2018

Aimed at increasing aircraft’s leaving speed based on a determinate length of aircraft container and ensuring the aircraft’s acceleration below one certain value, a new gas multi-stage cylinder ejection is proposed in this paper, and at the same time the primary design and the interior ballistic evaluating are processed. The simulation results can be used for the design of gas-catapult device and provide theoretical support for parameter optimizations in trajector.
Research on Key Techniques of the Verification and Testing System for Spacecraft Propulsion
Authors: Junwei Wang , Lei Zhang , Qingsheng Xiao , Gao Li , Xiao Han , Bing Bai
Published: July 2018

Electric propulsion is an important technology in the future space missions. The verification and testing system is mainly used for the manufacturers to fully understand the propulsion behavior in the most diverse conditions, and to indentify and eliminate potential failure modes to advance its validity and reliability, explore the applied potential for space missions. The paper presents a new verification and testing system for spacecraft propulsion and the key technologies needed to be developed are studied. The debugging data and research indicate that ultimate pressure of system is better than the 5.0×10-6Pa. Both the cold plate used for xenon pumping and sputtering protective system get an excellent performance in system. The DSMC numerical simulation method is verified that is beneficial to the research of optimization design and plume effect of electric propulsion in future.
Analysis of Operation of Throttle Micro-cooler at Nitrogen Use with Near-critical Parameters
Authors: Uglanov Dmitry , Sarmin Dmitry , Akulova Alina , Aksenova Daria , Dostovalova Sophia
Published: July 2018

The work of a throttle cooling system with a standard balloon and a throttle cooling system from a cryogenic filling balloon is considered. A comparison between the geometric and hydraulic characteristics of the micro heat exchangers of the two systems is made. The prospects of using the latest system for cooling of photodetector devices (PD) of the infrared range of navigation and research systems for aerospace applications are also shown.
Investigation of Flow over the Airfoil NACA 0010-35 with Various Angle of Attack
Authors: Xiao Shiming , Chen Zutai
Published: July 2018

This report is using the finite element analysis method to investigate the performance of an airfoil (NACA 0100-35), which uses 2D computational fluid dynamics simulations based on ANSYS to find the lift and drag coefficients under different conditions. The boundary conditions are defined as follows: The density is 1kg/m3, gauge pressure is 0, and airflow velocity is 50m/s. Also the Reynolds number is considered during the simulation. As a result, the simulation shows the stalling points and efficiencies of the airfoil under different angles of attack. The simulation also plots the contours and stream lines in these conditions.
Research on LDPC Coding for Free Space Optical Communication with Modified Bessel-Gaussian Beams Based on K-distribution
Authors: Wang Jin , Zeng Fujiang , Liang Qingqing , Zhang Xiaofeng
Published: July 2018

We investigate the performance of low-density parity-check (LDPC) coding for free space optical communication (FSO) with modified Bessel-Gaussian (MBG) beams based on K-distribution. Based on an extended Huygens–Fresnel principle, the receiver plane intensity isformulated and then we analyze the propagation characteristics of MBG beams traveling in aturbulent atmosphere. Numerical calculations show that the interaction of the transmissiondistance, refractive index structure constant, and wavelength will affect the imaginary term inthe beam, allowing the beam to exhibit the properties of the MBG beams. To further improvethe communication quality of the FSO system, we introduce a fast Quasi-Cyclic (QC)Low-Density Parity-Check (LDPC) code. Simulation results show that under weak and strong turbulence conditions, the performance of the QC-LDPC code becomes better and better as the code rate increases, and the bit error rate (BER) keeps decreasing as the code rate increases.
Optimization Design of Thermal Test Waveguide Link for Communication Satellite
Authors: SHAO Yu-jie , Zhong-xi Yu , DU Chun-lin , WANG Jing
Published: July 2018

Problems in structure of water load power meter and waveguide assemblies of the communication satellite transponder thermal test. This paper analyzes water load layout and reasons of signal attenuation, and then it proposes an optimization that put water load detached from satellite’s board. To ensure the reason of waveguide signal loss, this paper discusses the internal electromagnetic field distribution and currents on waveguide wall. the result of signal loss value showed that the new optimization can decrease signal attenuation value and shorten the process of crafts implementation.
Method Based on SEFT-to-Petri for Safety Analysis of Software
Authors: Sai-sai Xu , Jing Chen , Yu-ning Sun , Xin-rui Gao , Bo-han Wang , Kun-long Wang
Published: July 2018

System safety is a vital non-functional requirement whose satisfaction is essential for system software. However, modern aerospace system software is more and more complicated, which results in a high complexity of analyzing system faults. With the increased acceptance of Model-based Systems Engineering as a new method for systems engineering, Model-based Safety Analysis is also proposed to formalize the task of safety analysis and automate the safety calculations. Our work is grounded on State/Event Fault Tree to analyze system faults and build functional model. Firstly, we can translate SEFT to state machine based on SysML with fault syntactic messages and match elements together with translating logic gates; after which, transforming state machine into Petri Net model by means of rigorous semantic relations to extract preliminary analytical model is deduced theoretically in this paper; finally, we can derive analyses of causes and results of faults from Petri Net model by adopting a set of mathematical and statistical analysis. Practically, we have also validated our work by a case study of an aeronautic control system to support this paper.
Le respect des obligations légales et règlementaires du chirurgien-dentiste
Authors: Aknine B.
Published: July 2018

Le chirurgien-dentiste est soumis au respect des dispositions légales et réglementaires dans l’exercice de sa profession, puis au sein du cabinet dentaire proprement-dit et enfin en sa qualité d’employeur.

Aussi, le respect des obligations est-il pour tout professionnel de santé une obligation morale, éthique, déontologique et légale, dont le manquement est source de contentieux.

Afin de mieux appréhender les obligations du chirurgien-dentiste dans sa sphère d’activité, un exercice utilisant la qualité comme un outil permet d’adapter le mieux possible les obligations légales et réglementaires qui nous sont imposées dans notre exercice quotidien tout en stimulant le plaisir du travail bien fait et bien pensé.
Gestion du cabinet dentaire : l’avènement du management scientifique et adaptatif
Authors: Cochet R.
Published: July 2018

La professionnalisation de la fonction « management » dans les cabinets dentaires et tout particulièrement dans les cabinets de groupe et les cabinets spécialisés en orthopédie dento-faciale est devenue un enjeu majeur de leur viabilité économique. Or, la plupart des praticiens gèrent leur structure de soins et leur équipe de manière empirique et intuitive sur le modèle « patriarcal » en vigueur depuis des décennies dans les entreprises à taille humaine. L’unilatéralité décisionnelle, l’omnipotence et l’autoritarisme sont privilégiés au détriment d’un mode de management plus participatif et délégatif impliquant les forces vives et humaines du cabinet dans sa démarche d’amélioration continue (démarche Qualité). La conduite du changement organisationnel et l’adoption de méthodes de travail héritées du management scientifique s’imposent d’autant plus que les conjonctures sociales et économiques fragilisent de plus en plus la branche dentaire.
Transformer vos processus ressources humaines pour améliorer votre prise en charge du patient, votre qualité et vos résultats
Authors: Boukhobza A. , Etchebarne T.
Published: July 2018

L’objectif de cet article est d’identifier quels sont les processus ressources humaines à mettre en place au sein des cabinets d’orthodontie pour à la fois améliorer la prise en charge des patients, mais aussi la rentabilité de la structure tant en termes d’organisation que financièrement.

Le travail sur la cohésion des équipes va créer un engagement collectif qui dépend d’une part de la qualité du recrutement des collaborateurs, et ensuite des leviers de motivation mis en place au sein des équipes et entretenus dans le temps. Dans les équipes la collaboration intergénérationnelle doit être gérée et optimisée.

D’autre part l’orthodontiste dirigeant doit avoir une stratégie et des objectifs clairs pour pouvoir communiquer efficacement. Il doit par ailleurs connaître les outils de communication selon les circonstances pour faire passer les messages dont il a besoin.
Binding of Heparin Fractions to von Willebrand Factor: Effect of Molecular Weight and Affinity for Antithrombin III
Authors: Baruch D , Ajzenberg Nadine , Denis Cécile , Legendre Paulette , Lormeau Jean-Claude , Meyer Dominique
Published: July 2018

To investigate the influence of the structure of heparin on its binding to vWF, we compared heparin fractions of different molecular weight (MW) or affinity for antithrombin III (ATIII). We studied the interaction of purified 125I-vWF or plasma vWF, labeled with a pool of 125I-monoclonal antibodies to vWF, with unfractionated heparin immobilized on agarose beads. Fractions were compared as competitors of these interactions and their effect was quantitated by their half-maximal inhibition (IC50). When the MW of the fractions decreased, especially below 7500, their IC50 increased, indicating that the affinity of the fractions for vWF decreased with their MW. Using heparin-derived oligosaccharides, we also demonstrated that a minimal chain length of 18 monosaccharides was required for heparin binding to vWF. In addition, different fractions with low affinity for ATIII were compared as competitors of 125-vWF binding to heparin-agarose. Despite a very low content of ATIII binding sites, some fractions retained a low IC50. Thus, heparin interaction with vWF is independent of the presence of the ATIII binding site and is mostly dependent on the length of the heparin chain. These data suggest that unfractionated heparin is a more potent inhibitor of vWF-dependent functions than low MW heparin fractions.
Fibrinogen, D-Dimer and Thrombin-Antithrombin Complexes in a Random Population Sample: Relationships with Other Cardiovascular Risk Factors
Authors: Giansante Carlo , Fiotti Nicola , Cattin Luigi , Col Paolo Giovanni Da , Calabrese Salvatore
Published: July 2018

Fibrinogen is an independent risk factor for cardiovascular disease and both D-Dimer and Thrombin-Antithrombin complexes may be suitable as laboratory markers of deep venous thrombosis and are becoming more widespread in clinical practice. The aim of our study was to evaluate their normal range and to examine their correlation with various cardiovascular risk factors. Fibrinogen, D-Dimer and Thrombin-Antithrombin complexes were assessed in 516 normal subjects randomly selected from the National Health Service register of Trieste (Italy). In our community the mean value of fibrinogen was 283 ± 71 mg/dl. Fibrinogen increases with age in males and was significantly higher in male smokers. In non-smokers, females had significantly higher fibrinogen values than males. The mean value of D-Dimer was 306 ± 130 ng/ml. In females it is significantly higher. The fibrinogen and D-Dimer correlation coefficient was 0.20 (p < 0.001). The mean level of Thrombin-Antithrombin complexes was 6.25 ±6.8 ng/ml with a distribution markedly skewed towards the left; males had lower concentration than females (p = 0.047). Multiple regression analysis for fibrinogen as a dependent variable showed that D-Dimer, LDL- eholesterol, Body-Mass Index and Thrombin-Antithrombin complexes were poor predictors for fibrinogen plasma levels (R2 = 0.23) and that fibrinogen, ApoAl and age can explain only about 10% of the observed variability in D-Dimer.
Haemostatic Abnormalities Persist Despite Glycaemic Improvement by Insulin Therapy in Lean Type 2 Diabetic Patients
Authors: Knöbl Paul , Schernthaner Guntram , Schnack Christoph , Pietschmann Peter , Proidl Sylvia , Prager Rudolf , Vukovich Thomas
Published: July 2018

Diabetes mellitus is associated with disturbances of the haemostatic system, which might contribute to the development of diabetic vascular disease. We investigated the effect of metabolic improvement by insulin therapy on the haemostatic system in 61 patients with type 2 diabetes mellitus and secondaxy sulfunyluiea failure compared with 45 healthy control subjects matched for age, sex and BMI. Median age was 65, median diabetes duration 10 years. Median HbA1c (10%) and fructosamine (4.0 mM) levels were elevated before induction of therapy and decreased significantly within 6 months of insulin treatment to 7.5% and 3.0 mM, respectively (p <0.0001). Compared with control subjects, median plasma levels of fibrinogen (317 vs 286 mg/dl), coagulation factor VII activity (1.1 vs 0.89 U/1), von Willebrand factor (1.6 vs 1.3 U/1), D-dimer (105 vs 86 jug/1), protein C:Ag (1.24 vs 0.95 U/1), total protein S:Ag (1.15 vs 0.91 U/1), and antithrombin III activity (1.17 vs 1.08 U/1) were significantly elevated. Levels of free protein S were not different from control values. No significant decline of coagulation parameters could be recorded during insulin therapy. Patients with diabetic vasculopathy had higher levels of D-dimer than those without (133 vs 76 μg/1 before, 109 vs 88 μg/1 during therapy), whereas the other haemostatic parameters were not different. Our data indicate a significant activation of the coagulation system in diabetic patients with secondary failure to sulfonylurea drugs, with signs of a prethrombotic state and endothelial cell disturbance. Induction of insulin therapy results in a significant improvement of glycaemic and lipid metabolism, but the persisting enhanced activity state of the haemostatic system might contribute to the increased cardiovascular mortality of type 2 diabetic patients.
Hereditary Protein C-Deficiency: Laboratory Values in Transmitters and Guidelines for the Diagnostic Procedure Report on a Study of the SSC Subcommittee on Protein C and Protein S
Authors: Pabinger I , Allaart C F , Hermans J , Briët E , Bertina R M ,   The Protein C Transmitter Study Group
Published: July 2018

A multicenter study on protein C-antigen and -activity values was carried out in transmitter patients with hereditary protein C deficiency (diagnosis established by pedigree analysis) and in normal controls in order to (1) establish the range of protein C levels in genetically determined heterozygotes and (2) to evaluate the usefulness of statistical procedures to discriminate between protein C deficient patients and controls. In transmitters absolute protein C activity values ranged from 19 to 82% and antigen values from 22 to 88.5%. Most transmitter patients could clearly be differentiated from the control group. However, in some transmitter patients values of protein C were within the range of the control group. The discrimination between transmitters and controls could be improved by statistical procedures. Using tolerance ellipses the overlapping area of the two groups was smallest when (factor II antigen + factor X antigen)/2 was plotted against protein C antigen. To specify the degree of uncertainty likelihood ratios were calculated to obtain the posterior probability for an individual for being deficient or not. In quadratic discriminant analysis the best discrimination between transmitters and controls was obtained using protein C activity versus factor X antigen and protein C antigen versus factor X antigen. Based on these analysis an equation was derived, which allows the calculation of the likelihood ratio favouring deficiency or non-deficiency in an individual.