bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of differential evolution algorithm in the problems of gliding descent optimization
Authors: Elisov N A
Published: November 2020

Despite the closure of the Space Shuttle program, spaceplane remain a promising vehicle, which is being developed in many countries, such as USA, European Union and China. Interest in spaceplane is due to the possibility of their reusability and wider maneuverability in comparison with reentry capsule. However, it’s reusability is directly related to satisfying the temperature limit while descending from orbit. Also, the spaceplane has ricochets in its trajectory due to a high lift-to-drag ratio that decreases landing accuracy. The paper aim is the synthesis of an optimal control program in the problems of gliding descent to the maximizing longitudinal range and lateral range with temperature limitation and the absence of ricochets. The synthesis of the optimal trajectory can be obtained by the control channels of attack angle and bank angle. The approach is to represent the control channels of attack angle and bank angle in the form of Fourier series, and the search for the optimal solution is carried out using the differential evolution algorithm. The paper presents the results of solving problems using a different number of the Fourier series terms.
Change of mechanical structures of spacecraft with variable quantity of degrees of freedom in purposes of reaction/momentum wheels unloading
Authors: Doroshin A V
Published: November 2020

The using of the released (“defreezed”) additional degrees of freedom is considered to control by the relative angular momentum of reaction/momentum wheels and to unload this relative angular momentum. The change of the relative angular momentum of wheels is fulfilled with the help of its translation to additional internal rotors and main body of spacecraft.
Comparative analysis of algorithms for ship pitching forecasting
Authors: Antonov D
Published: November 2020

An overview and analysis of various ship motion prediction algorithms based on its description by random or quasideterministic processes are carried out. The testing of real data is conducted to estimate the performance of algorithms.
Fusion of inertial and optical data for monitoring the geometry of the rail track
Authors: Boronakhin A M , Filatov Yu V , Larionov D Yu , Podgornaya L N , Tkachenko A N , Shalymov R V , Yen Nguyen Trong
Published: November 2020

Methods and means of monitoring the state of the rail track by a number of key geometric parameters are analyzed. The concept of joint use of inertial and optical technologies as an accurate and cost-effective solution in this area is proposed. An assessment of the influence of errors of individual measuring modules of an optical-inertial diagnostic system on the accuracy of determining the geometric parameters of a rail track has been carried out. Questions related to the recognition of the rail image in the readings of optical sensors against the background of stray lighting and sun glares are touched upon. Attention is paid to the methods of obtaining a priori data on the position of the rail head profile on the matrix of the scanner camera. The results of experimental testing of the proposed solutions are presented. The current approach to the indirect assessment of the dynamical behavior of a railway mobile unit’s bogie in a track is analyzed. An approach is proposed for direct control of this dynamics without introducing an intermediate parameter of equivalent conicity.
Digital Excitation Channel for Ring Micromechanical Gyroscope
Authors: Goncharov I K , Mayorov D V , Kostornoy A N
Published: November 2020

This research is devoted to the design of a digital excitation channel for a ring micromechanical gyroscope. The main methods of excitation of oscillations in angular rate vibration sensors were considered. The possibility of using a self-oscillating mode of operation for a ring resonator has been demonstrated. A mathematical model of operation of such system was created for this purpose. Besides a prototype electronics was built. It has experimentally confirmed the operability of the digital oscillation excitation channel and the possibility of stable maintenance of the oscillation velocity amplitude.
Technologies of microsystem technique and nanosensorics
Authors: Pavelyev V S , Tukmakov K N , Agafonov A N , Tripathi N , Kumar S
Published: November 2020

Present article deals with microsystem technology and nanosensors. We covered the properties and synthesis technology of Carbon Nanomaterials. The detailed discussion has been made on synthesis of Carbon Nanotubes by thermal chemical vapour deposition (CVD) while reduced graphene oxide by modified Hummers method. Further, as grown Carbon nanomaterials have been used for developing optical detector for visible to near infrared range and Nitrogen Dioxide gas sensor.
From micro to nano. Problems of modeling of nanoelectromechanical sensors
Authors: Barulina M A , Galkina S A , Markelova O V , Golikova O V
Published: November 2020

Microelectromechanical (MEMS) sensors are a class of devices that appeared relatively recently, only 50-60 years ago but are widely used in various fields of science and technology due to such characteristics as small sizes, low power consumption, and sufficient accuracy. The next step in miniaturization led to the creation of nanoelectromechanical sensors (NEMS) – measuring instruments that combine electronic and mechanical components that do not exceed 100 nm in size. On the one hand, the development and manufacture of NEMS require a high level of nanotechnologies. On the other hand, the development and manufacture of NEMS lead to the development of new materials with new effects such as surface and quantum effects. At the same time, the range of tasks that can be solved with using NEMS is quite wide – it’s expecting that the mass implementations of NEMS sensors and devices on their base can significantly improve the quality of people’s life, expand their physical capabilities, or compensate disadvantages. For NEMS, as well as for MEMS, such issues as temperature influence, electronic and mechanical noises, the possibility of chaotic outside signal appearance, and so on are relevant. However, because of the small sizes of NEMS, classical approaches may not be fully applicable to solving these issues. Besides that, during the NEMS design, the bunch of specific problems that not relevant for MEMS has appeared. The article provides a brief review of the state of developments in the area of NEMS sensors and problems that significant for NEMS due to their small size.
Optimization of ekranoplane flight control over the waved sea
Authors: Nebylov A V , Knyazhsky A Yu , Nebylov V A
Published: November 2020

The paper proposes to minimize the average altitude of the ekranoplane due to the desire to circumvent the low-periodic components of sea waves with smooth vertical maneuvers. To evaluate the effectiveness of the proposed method for optimizing the trajectory, a model was developed consisting of four blocks: simulation of sea waves, simulation of the operation of the measurement and control system of a ekranoplane, modeling the dynamics of the movement of an UAV, and evaluating the effectiveness of altitude minimization. The simulation results showed the possibility of reducing the average altitude of ekranoplane by 0.65m in 6-point sea waves. Also, the overload caused by vertical maneuvers did not exceed 0.16 g, which is acceptable for the transportation of most goods and people
Analysis of the influence of the error of the nanosatellite design and dynamic performances on the quality of angular motion control processes
Authors: Belokonov I V , Kramlikh A V , Melnik M E
Published: November 2020

By the nanosatellite angular motion control in this research is meant terminal control based on inverse dynamics problem solution using the Bellman’s optimality principle. The impact of the error of the nanosatellite design and dynamic performances, which are torques of inertia, attitude angles and angular rates, on the quality of angular motion control processes (i.e. on the accuracy of its reorientation), is investigated. The results of numerical simulation are given through the example of the nanosatellite of the SamSat family.
Taking into account constraints on magnitude and first derivative of the Global Navigation Satellite Systems differential corrections during their forecasting
Authors: Zaitsev O V
Published: November 2020

Algorithms for predicting differential corrections to GNSS measurements have been developed, the low labor intensity of which allows them to be applied in real time. The processing of corrections before the break is performed using the Kalman filter in reverse time. The interval of processed corrections gradually expands as the forecast duration increases. Based on the results of experiments with field GNSS data, a comparison of the algorithms efficiency was made.
Accuracy improvement for GNSS -based compass
Authors: Shafran S V , Kudryavtsev I A
Published: November 2020

To calculate relative position of two navigation antennas with a relatively short baseline phase measurements are commonly used. This approach is associated with technical difficulties related to the synchronization of receivers and resolution of phase ambiguities. Double phase differences of eliminate these errors and therefore allow to calculate the azimuth with better accuracy. Proposed algorithm for phase ambiguities resolution consists of three steps: applying double phase difference model insensitive to full phase due to the usage of cosine function, secondly using differential evolution method to fit model to observation by varying orientation angles and finally computing phase ambiguities from roughly estimated angles. To reduce the phase centre shift influence on azimuth computation error, the correction function depending on navigation signal arrival angles was introduced. To find its numerical values, the experiment with rigidly fixed antennas was carried out. Its idea was to take into account the relative movement of navigation satellites in fixed antenna system. Development of a multi-antenna navigation receiver with an additional channel for calculating phase ambiguities is described.
Application of the polynomial filtering algorithm to identification of the narrowband process parameters
Authors: Vasiliev V A
Published: November 2020

A polynomial filtering algorithm has been implemented to identify the central frequency and correlation interval of a narrowband process. The efficiency of the polynomial filtering algorithm is carried out by comparing it with the potential accuracy calculated using the algorithm based on multi-alternative filtering. Recurrent relations are proposed for determining the lower bound of accuracy for estimating the parameters of a narrowband process. The possibility of using less computationally expensive procedures for calculating the lower bound of accuracy is investigated.
Software-defined Radio GNSS Receiver Signal Tracking Methods
Authors: Kumarin A A , Kudryavtsev I A
Published: November 2020

Software-defined radio (SDR) - based GNSS receivers are flexible. SDR technology allows changing processing algorithms and adding new signals without any hardware modifications. The main drawback of such a receiver is high computation load. Signal tracking module takes most part of CPU time. This paper considers distributed receiver architectures where most of the processing is performed in a remote PC or a server.

The amount of raw data in the SDR receiver is too large for complete transfer. Two methods of reduction are discussed: truncating epochs and disabling tracking for a certain period. The limitations of each method are estimated using simulations. Epochs can be truncated by 50-75% depending on signal-to-noise ratio. The maximum disabling time is about 0.5s for a stationary receiver and 0.1s for a car receiver. Using both methods in combination reduce data volume by 95.4% for a stationary receiver and 83.3% for a car receiver.
Requirements for nanosatellite-mounted GNSS-based instrument measuring ionospheric total electron content
Authors: Nikolaev P N , Kudryavtsev I A , Shafran S V
Published: November 2020

A navigation receiver mounted on board of a micro/nanosatellite can be used as part of a scientific instrument for ionospheric study, for instance, identification of patterns in solar-terrestrial links and obtaining a set of statistical data to find the correlation between local fluctuations of the ionosphere and climatic changes. Such a device should produce an array of navigation measurements of carrier phases and pseudoranges, and also calculate on their basis the values of the absolute total electron content (TEC), which are used to study the ionosphere. To calculate the absolute TEC, we use a known technique that combines carrier phase and pseudorange measurements. Taking into account the peculiarities of this technique and the geometry of the measurements, we put forward a number of requirements for a scientific instrument to study the ionosphere.
Nanosatellites Formation Flying Control Approaches Overview
Authors: Ivanov D , Ovchinnikov M , Tkachev S
Published: November 2020

The paper considers various approaches nanosatellites formation flying control, presents dynamic models of the motion of a group of nanosatellites, considers various algorithms for controlling relative angular and translational motions, taking into account the specifics of small satellites and limited inter-satellite communication capabilities. The paper discusses various approaches to the formation flying control, including those using perspective methods that do not require the fuel consumption. With a large number of spacecraft in a group, a new class of space systems appears, defined as a swarm. The main difficulty in implementing a swarm formation flying of satellites is navigation and control of the mutual relative motion of an individual satellite in a swarm, taking into account the fundamental impossibility of having information about the phase state vector of each swarm element. The features of decentralized algorithms for controlling the satellites swarm motion are considered and the dynamics of the swarm is investigated.
Approximate optimal method for controlling the angular motion of a spacecraft as part of an orbital tether system
Authors: Zabolotnov Yu M
Published: November 2020

An approximate optimal method for controlling the movement relative to the center of mass of a spacecraft as part of an orbital tether system is considered. The purpose of the control is to stabilize the spatial angular movement of the spacecraft relative to the direction of the tether connecting it to another spacecraft. If there is no control, the angular movement of the spacecraft relative to the direction of the tether may be unstable. This is primarily due to the disturbances that occur during the formation (deployment) of tether systems, as well as the internal small mass asymmetry of the spacecraft that inevitably occurs during its manufacture. An approximate optimal method for stabilizing the relative motion of a spacecraft on a tether is proposed, based on the Bellman dynamic programming principle and the averaging method. The averaging method is used for approximate solution of the Bellman partial differential equation, which allows in many cases to obtain the regulator’s equations in analytical form. An example of the application of this approach to stabilize the movement of a small spacecraft when deploying an orbital tether system is given.
Stabilization of the rotational motion of a composite nanosatellite with a mobile module mounted on a rotating platform
Authors: Doroshin A V , Eryomenko A V
Published: November 2020

The paper considers the dynamics of the spatial motion of a composite nanosatellite with a movable module making an angular deviation relative to the carrier body. Control laws have been developed to stabilize the rotation of the nanosatellite relative to the longitudinal axis.
Laboratory Study of the Active Debris Removal Algorithms on Air-Bearing Test Bed
Authors: Mahdi Akhloumadi , Filipp Kozin , Ivanov Danil
Published: November 2020

Space debris removal is one of the most important problems in space exploration. This work is devoted to the development and testing of control algorithms for microsatellites mockups on an aerodynamic table. The mock-ups are equipped with thruster’s simulators to control the motion of the center of mass and angular motion on the plane of the table. The aim of the work is to construct a control algorithm using virtual potential functions and apply it to the problems of rendezvous and docking. Simultaneously with these tasks, the problem of avoiding a collision with an object in the event of a dangerous approach not from the docking side is solved. Also the algorithm for autonomous debris observation of the 3U CubeSat is proposed. The results of the control algorithm tests are presented in the paper.
Influence of temperature restrictions on the heliocentric motion controlling of a solar-sailing spacecraft
Authors: Chernyakina I V , Rozhkov M A , Starinova O L
Published: November 2020

Solar sailing spacecraft uses the light pressure to change the trajectory and are most effective in the immediate Sun vicinity, but the sail surface temperature most significant increases in the same area. Therefore, when designing solar sailing “hot” missions, we should consider the temperature restriction when choosing the control laws. The paper proposes the following approach to the implementation of the temperature restriction. When exceeding a predetermined temperature limit values the sail deviates from the direction of the radiation flux so that the direction of the acceleration projection on the Ecliptic plane is not changed, but the total sail orientation angle increased. The additional acceleration that occurs when using this approach, directed along the Ecliptic normal, can be used to rotate the orbital plane, if this is necessary to fulfill the flight purpose or to form a cylindrical orbit.
Analysis of the deployment of a three-mass tethered satellite formation
Authors: Chen Shumin , Li Aijun , Wang Changqing
Published: November 2020

Tethered satellite formation has obtained widespread attention in recent years. The main causes of the increasing study interest around tethered formation lie in its promised applications in space, such as interferometric measurements. The deployment of a tethered formation system in low Earth orbit is investigated in this paper. The orbital tethered system consists of three nanosatellites connected via tethers end-to-end, and the desired arrangement for the end masses is an equilateral triangle. For the sake of brevity, the formation system is modeled as a particle-rigid rod system, in which the elasticity of the tethers is omitted. The deployment process is carried out using tension forces and active external forces generated by low-thrust engines. The numerical results confirm that it is possible to deploy a triangular tethered system, which rotates at a given initial angular velocity, to an expected arrangement using the proposed control law of tether tensions and active forces.
Motion control of a space robot at launching and approaching a geostationary satellite
Authors: Starinova O , Somov Ye , Butyrin S
Published: November 2020

The problems of putting a space robot into a geostationary orbit using a combined scheme and its approach to an information geostationary satellite are considered. When approaching, the robot’s attitude and orbit control system uses an electric propulsion unit, a propulsion system based on eight electro-catalytic reaction engines with pulse-width modulation of their thrust, and a gyroscopic moment cluster based on four single gimbal control moment gyroscopes (gyrodines). Numerical results are presented that demonstrate the effectiveness of the developed discrete guidance and control algorithms.
Investigation and selection of a functional in the problem of synthesis of an optimal control law providing inspection motion
Authors: Shcherbakov M.S. , Ananev A.V. , Avariaskin D.P.
Published: November 2020

In this paper we consider the problem of keeping a nanosatellite near the nominal inspection ellipse, which is the Hill ellipse. The source of the disturbing effect, leading to the deformation of the nominal trajectory, is the drag of the atmosphere and the nonlinearity of the central attraction field. Using the traditional approach to finding the control law in the form of a linear-quadratic controller does not always meet the specified requirements, since it is based on the formation of a control law based on a linearized model of motion dynamics. The method of control law synthesis in the form of a linear-quadratic controller, using a quasilinear model of motion (SDRE-method), allows to increase the accuracy of the implementation of the inspection motion. In this work, a study was carried out to select the parameters of the quadratic quality criterion from the conditions to provide the requirements for energy costs and the quality of implementation of the inspection motion.
Control system and optimization of parameters of a closed biosystem the size of a pico-satellite
Authors: Mastalieva V A , Perliouk V V
Published: November 2020

The paper researched the sustainable functioning of the closed self-regulating biological system based on macrophytes Fucus vesiculosus, Fucus inflatus, Laminaria saccharina and Chlorella vulgaris. The authors describe the methods and apparatus for monitoring the composition and control of biological experiments with such a system, which is offered to spend on board the International Space Station (ISS). We also consider the option of the experiment on board the small satellite. The main task of automatically controlled experiment is to ensure the long-term functioning of the isolated biological system under conditions of weightlessness. Based on the analysis of the interaction structure of the main components of biological systems under study was developed a mathematical model of a closed biological system on the basis of aquatic organisms and holds its computer simulation, with which defined the conditions for the forecast can be carried out and state control investigated the conditions of maintaining it stable life. We consider the automated control system of a biological system, providing its stable operation. The main indicator of the functioning of biological systems encouraged to use the amount of oxygen in the air section and dissolved in water. As a biological control system parameters used by the lighting level and temperature of the water environment. In the experiment on autonomous spacecraft (microsatellite) proposed to manage the dampers in the heat-insulating sheath. The dependencies for defining the threshold oxygen concentration at which a correction of the control parameters.
Analysis and design of halo orbits in cislunar space
Authors: Chongrui D , Fain M K , Starinova O L
Published: November 2020

This paper examines the formation of halo-orbits by a spacecraft around L1 and L2 libration points of the Earth-Moon system. Perturbations from the gravitation of the Sun and the non-centrality of the gravitational fields of the Moon and the Earth are taken into account (LP165p model). The proposed perturbed model is an intermediate stage between the dynamic model of the three bodies of the Earth-Moon system and the high-precision non-periodic ephemeris model. The paper proposes two strategies for maintaining halo orbits. The first is to use a small impulse performed on each half of the orbit. The second is to use continuation methods to form a periodic orbit that does not require additional corrections. The essence of the second strategy is to use the perturbation periodicity to generate a special multi-circular halo orbit resonating with the perturbation period. The results of these two approaches are presented for various perturbed models.
Support subspace method and conforming estimation in autonomous navigation tasks
Authors: Fursov V A , Minaev E Y , Kotov A P , Zherdev D A
Published: November 2020

The article discusses the technology of autonomous navigation by optical observations. A scheme based on the recognition of three-dimensional landmarks is considered. To improve the accuracy and reliability of recognition, a survey model is constructed for each landmark. When calculating the parameters of this model, the most conformed data is selected. The problem of recognition is solved using the method of support subspaces. Support subspaces are formed from a set of vectors of each reference landmark. An important advantage of the technology is the ability to refine the landmark models based on the results of current observations during operation.
Functional and test diagnosis of onboard systems using dynamic models
Authors: Lukoyanov E V , Gruzlikov A M , Kolesov N V
Published: November 2020

The paper discusses the problems of troubleshooting in onboard computing and control systems. Herewith the approaches based on the methods of functional and test diagnostics are analyzed. Both approaches involve the introduction of redundancy, which in fact is a dynamic software model of the systems being diagnosed. In the case of functional diagnostics, a full-fledged model is used that forms the basis for diagnostic observers; in the case of test diagnostics, it is a simplified event model.
Application of artificial intelligence technology in the nanosatellite attitude determination problem
Authors: Belokonov I V , Kramlikh A V , Melnik M E
Published: November 2020

The paper proposes an approach of the nanosatellite attitude determination problem solution using elements of artificial intelligence technology. This approach consists in the reconfiguration of the algorithms of the nanosatellite attitude determination problem solution based on the knowledge database that can be enriched to ensure the robustness of the feedback loop (the nanosatellite attitude determination using different combinations of different types of measurement information by various algorithms). This research results are presented in relation to the nanosatellite of the SamSat family: values of measurement significance coefficients are chosen; then generalized algorithm significance coefficients are calculated for various combinations of operable measuring means using chosen coefficients.
Sensitivity analysis for filtering with preliminary processing of measurements
Authors: Titov R , Motorin A
Published: November 2020

The sensitivity of estimation algorithms to the parameters of the preliminary filter is analyzed, using the problem of gravity anomaly estimation using a damped gravimeter as an example. Two models for preliminary filter are considered, which corresponds the models for gravimeter sensitive element in the example. First is a physically substantiated elastic pendulum model. Second is its simplified version in the form of a first-order system model. The results of the sensitivity analysis of gravity anomaly estimation accuracy to the models are presented.
Procedure of experimental evaluation of nanoclass spacecraft design parameters using the ground test equipment
Authors: Belokonov I V , Kliuchnik V N , Barinova E V , Ivliev A V , Boltov E A
Published: November 2020

As it is impossible to set high accuracy of the initial data for theoretical calculations of the design parameters, such as the mass-centering and inertial characteristics of nanosatellites, the problem of experimental determination of their actual values arises. For a number of reasons, the devices designed for large spacecraft are not appropriate for the small ones. This paper describes a device developed at Samara University for measuring the center of mass coordinates and moments of inertia specifically for CubeSat nanosatellites, as well as a technology for experimental evaluation of the design parameters of nanoclass spacecraft. The accuracy of determining the design parameters using the proposed device is confirmed by a series of experiments with standards.
Probabilistic analysis of maneuvering nanosatellites with electrothermal propulsion system
Authors: Sinitsin L I , Belokonov I V
Published: November 2020

A method is proposed for assessing the results of correction maneuvers for a nanosatellite (NS) with an electrothermal propulsion system (ETPS). Common causes of maneuvering errors associated with technological errors in creation of the propulsion system and the nanosatellite as a whole are revealed by an example of the SamSat-M NS being under development. The analysis of the NS maneuvering process was carried out in a probabilistic setting. A factor analysis is carried out and the contribution of the design parameters of the NS and ETPS to the spread of the projections of the velocity increase vector of the NS motion and the arising angular motion is determined.
Thermophysical properties of [EMIM][BF4] and [HMIM][PF6] imidazolium ionic liquids with MWCNTs
Authors: Hasen Huda Majid , Abdulmajeed Basma A.
Published: November 2020

In this study, several ionanofluids (INFs) were prepared in order to study their efficiency as a cooling medium at 25 °C. The two-step technique is used to prepare ionanofluid (INF) by dispersing multi-walled carbon nanotubes (MWCNTs) in two concentrations 0.5 and 1 wt% in ionic liquid (IL). Two types of ionic liquids (ILs) were used: hydrophilic represented by 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] and hydrophobic represented by 1-hexyl-3-methylimidazolium hexafluorophosphate [HMIM][PF6]. The thermophysical properties of the prepared INFs including thermal conductivity (TC), density and viscosity were measured experimentally. The TC measurement showed an enhancement of about 3% for INF and of 1% MWCNT in [EMIM][BF4] at a temperature of 298.15 K: the TC was 0.186 W/m.K, the kinematic viscosity was 100 centistokes (cSt), and the density was 1.283 g.cm−3. On the other hand, the TC of 1% MWCNT in [HMIM][PF6] INF enhanced by 5%. In this case, at a temperature of 298.15 K, the TC was 0.158 W/m, the kinematic viscosity was 1200 cSt, and the density was 1.294 g.cm−3. Furthermore, the stability of the prepared INFs was measured using the zeta potential method after 28 days of preparation. The results show very good dispersion of the nanoparticles in the ILs for all the prepared INFs. The zeta potential was -69.30 mV and - 45.34 mV for 0.5% and 1% MWCNT in [EMIM][BF4], respectively. On the other hand, zeta potential was -51.78 and -46.67 mV for 0.5% and 1% MWCNT in [HMIM][PF6], respectively. According to the obtained results, the preferable INFs to use as a cooling medium at 25 °C was the INF of 1 wt% MWCNT in [EMIM][BF4], since it provides better thermophysical properties than the other prepared INFs.
Kevlar-based Composite Material and its Applications in Body Armour: A Short Literature Review
Authors: Nair Anand Narayanan , Sundharesan Santhosh , Al Tubi Issa Saif Mohammed
Published: November 2020

Kevlar is a synthetic fibre which has gained worldwide attention due to its numerous industrial applications. It is mostly used in combination with other materials and acts as an effective composite material. Scientifically known as poly(p-phenylene terephthalamide), the Kevlar monomer has 14 carbon atoms, ten hydrogen atoms, two nitrogen atoms and two oxygen atoms. A Kevlar polymer chain can have monomers ranging from five to one million bonded to each other with a molecular formula of [-CO-C6H4-CO-NH-C6H4-NH-]n, where n represents the number of monomers. Kevlar has a wide variety of applications ranging from bicycle tyres to aerospace applications. Based on the applications, Kevlar fibres are graded in various ranges. This paper provides insight into major research on Kevlar, especially in defence applications.
The Mechanical Properties of Aluminium Metal Matrix Composite (AlMMCs) Reinforced with Ni and SiCp
Authors: Naeem Haider Tawfiq
Published: November 2020

This investigation studies the effects of nickel (Ni) particles combined with silicon carbide (SiCp) particles on the microstructural and mechanical properties of aluminium(Al)-magnesium(Mg)-manganese(Mn) matrix alloys under different sintering temperatures. The Al-Mg-Mn-SiCp/Nip composite samples were produced via the powder metallurgy route. The sintering process was performed on a green compact of Al-Mg-Mn matrix/SiCp/ or Nip composites at 400 °C and 600 °C for 1.5 hours at a constant heating rate of 50 °C/min. The Al-Mg-Mn-SiCp/Nip samples were evaluated and characterised using a scanning electron microscope and X-ray diffraction. Additionally, the Al-Mg-Mn-SiCp/Nip samples were measured for Vickers hardness and compressive strength. The outcomes show that Al-Mg-Mn-5%SiCp-6%Nip gave the highest Vickers hardness. The results showed that the optimal sintering temperature performed on the Al-Mg-Mn-SiCp/Nip sample was 400 °C compared with 600 °C because the overall dissolution of alloying elements within the Al-matrix led to an enlargement of grains, thus, reducing their mechanical properties.
Evaluation of Mechanical Properties of Composite Laminates by Fractal Dimension
Authors: Mahmood Amjed Saleh
Published: November 2020

This study focuses on the evaluation of mechanical properties of composite laminates by fractal dimension (FD). The fibre distribution in a laminate or FD could be changed according to different manufacturing processes, such as hand lay-up, resin infusion and resin transfer moulding. These manufacturing processes are considered in this study. Woven Kevlar / epoxy composite panels were manufactured with a [0/90]2S stacking sequence. The materials were characterised for interlaminar shear strength (ILSS) and flexural strength. The fibre volume fraction (Vf) and FD of the laminates were determined from optical microscopic images of polished cross-sections using ImageJ software (box counting method) with the Fractal and Lacunarity add-in. The results show significant relationships between the mechanical performance of the composite laminates and the FD.
Rheological and Mechanical Investigation of PET, LDPE and HDPE Wastes Blended for Re-Use in Bio-Pipes
Authors: Jabir Ruqaya Khairy , Hadi Nizar Jawad , AL-Zubiedy Ali Abd-Alameer
Published: November 2020

This work focuses on the re-use of biopolymer wastes to produce the pipes and reduce the impact of these materials on the environment. The ratios of 10, 20, 30 and 40wt% of recycled polyethylene terephthalate (RPET) were added to the reference blend, which consists of recycled low-density polyethylene (RLDPE) and recycled high-density polyethylene (RHDPE). Rheological and mechanical tests were performed on these blends. The blend of RLDPE and RHDPE was already successful in the manufacturing of pipes. The capillary rheometer was used to check the shear viscosity and shear stress behaviour with the shear rate increasing for different blends. The density, tensile strength, elastic modulus and impact strength were also tested for all blends. The results showed that the shear viscosity decreases and the shear stress increases with the shear rate increasing for all blends. In general, the addition of RPET to the reference blend decreases the viscosity at each shear rate. The blends of ten wt% and 20wt% are more compatible with the reference blend, while the blends of 30wt% and 40wt% exhibit a clear deviation after a shear rate of 300. The density indicates an increase with the increase of RPET to the reference blend. The tensile strength increases and impact strength decreases with the increase of RPET up to 30%. After that, the tensile strength decreases and impact strength increases up to the 40wt% RPET. The results showed that the rheological test can be used to predict the mechanical behaviour. Additionally, there was a good agreement observed between the rheological and mechanical tests. The ten wt% and 20wt% blends were more suitable for this task.
The Rheological Properties of LDPE Nanocomposites per a Capillary Rheometer: An Experimental and Numerical Study
Authors: Latef Zahra B , Hadi Nizar J , Saad N A
Published: November 2020

Rheological properties are very significant in determining processing performance. The increase of only a few percent of nanoparticles by weight will result in substantial improvement in rheological properties. This work focuses on studies of shear viscosity, shear stress and pressure at a shear rate range of (3-1500) s−1 and temperature of 170 °C. The flow properties of low-density polyethylene melt and nanocomposite experimentally studied in a single-bore capillary rheometer with a length-to-diameter ratio of (10:1) and numerically using POLYFLOW-Ansys version 15.0 software based on the power-law model. The experimental results show that the viscosity of nanocomposites decreased while the shear stress increased with the shear rate increase. The pressure drop decreases with the shear rate increases for all additional ratios. The experimental and numerical studies of polymer nanocomposites in a capillary die, the shear viscosity, shear stress and pressure behaviour numerically reveal good agreement with the corresponding experimental results.
Preparation of Sustainable Thermal Insulators from Waste Materials
Authors: Mashkoor Iman A. , Mohammad Haider M. , Dakhil Saadoon F.
Published: November 2020

This work aims to produce an experimental and theoretical analysis of thermal insulator specifications for buildings with sustainable requirements. In the experimental work, three categories of thermal insulators were prepared from composite materials, and each category had ten models. These composites included the addition of two types of waste (sawdust and tyre waste) as fillers for two types of matrices (liquid polyurethane and polyurethane foam) to obtain composite materials for thermal insulation samples. The prepared samples were subjected to tests to show their thermal properties, such as thermal conductivity and specific heat capacity as well as undergoing a hardness test. The theoretical analysis included the discovery of empirical equations for thermal properties as functions of two variables (temperature and mass ratio) and hardness as a function of one variable (mass ratio). A genetic algorithm optimisation technique was used to find the optimum mass ratio of the composite that produced the required insulation specifications. The results showed that thermal conductivity decreased when the sawdust mass ratio and the rubber waste mass ratio increased but remained under the thermal insulation range. Furthermore, the prepared insulator samples showed an improvement in thermal storage and the hardness of tyre waste (liquid polyurethane composites) and sawdust (polyurethane foam composites). Finally, optimum results were obtained using the optimisation technique.
Manufacturing of High-Load Engine Mounts From Rubber Composites (Natural Rubber and Carbon Black) with Novel Properties
Authors: Subeh Ahmed Abdulameer , Al-Maamori Mohammed H. , Hamzah Ahmed Fadhil
Published: November 2020

This paper explains the successful and simple process of generating a rubber mount with novel properties by incorporating carbon black particles type ISAF 220 at different ratios ([46, 56, 66, 76, 86] [pphr]). Rubber mounting was made using 100 % natural rubber and carbon powder that was applied to the master batch ratio (60 g). To achieve greater homogeneity, rubber and carbon were combined for several minutes. The rubber mount has been subjected to several tests at Babylon tires factory and Babylon University (tensile, elongation, modulus, compression, hardness, rebound resilience, specific gravity and fatigue tests). The best results were obtained from the rubber mount, as it had the ability to resist fatigue and could be used for a long period of time. It could also increase the number of cycles to 900 rpm. The rubber mount that was reinforced with carbon had a better resistance to the mechanical properties (tensile, hardness, fatigue and resilience). The results of the tensile strength, hardness, fatigue and resilience tests showed that additional quantities of carbon at 66 pphr increased the values by up to 18.95 Mpa, 64 Mpa, 600 Mpa and 55.5 Mpa, respectively.
Measurement of Alpha Activity in Several Types of Iraqi Ceramic and Cement in the Iraqi Markets
Authors: Awad Eman Ibrahim , Al-Rubaye Shymaa , Jebur Azhar Lateef , Hadi Abbas Fadhel , Awad Nagwa Ibrahim
Published: November 2020

In this study fifteen samples of ceramic and cement collected from Iraqi markets have been determined for the radium efficacy and radon exhalation rates using the CN-85 plastic track detectors. For the estimation of the effective radium content and exhale rate, these samples comprised 15 different Iraqi materials. The effective radium content values ranged from 2.108 to 21.689 Bq / kg to an average of 9.399 Bq / kg and standard devolution of 6.950. The mass exhalation levels for radon ranged from 0.106 to 1.092 mBq / kg.day, with an average value of 0.473 mBq / kg. day and standard deviation of 0.312 Bq / kg. The exhalation rate for the radon surfaces ranged from 1.889 to 19.44 mBq / kg.day. The mean radon exhalation levels, which are an effective radium element, were found to fall below the world average of 57600 Bq / m2 in the samples of ceramic and concrete materials and Soil: 35 Bq / kg, In addition, the study’s showed that the effective radium content in this study and the associated radon exhalation do not pose a human health risk when they are used in daily life in Iraqi markets.
Characterisation of Fe Doped Layered Cathode Material as Nano-Rechargeable Batteries
Authors: Abaas Rusul A.Rsool , Haider Adawiya J. , Jabbar Faten Abdul , Hathal Mustafa Mohammed
Published: November 2020

This research focuses on the layered doped lithium conductive metal oxides with the universal form Li MO2(M = Co, Ni, Ag or Fe doped solutions) adjustment of cathode electrodes for lithium-ion cells (LIBs). Preparation in a low temperature combustion reaction promotes its electrochemical efficiency. The modification starts with the preparation of the LiCo0.5Ni0.45Fe0.5O2 (LCNFO) powder with citric acid, which is used as fuel, along with deionized water (DW). As binding materials, nitrate of ions (Li+) and ions (Fe+) were added to this mixture to create a uniformed mixture. The required amount of citric acid and de-ionised water was added to this unified mixture to create a powder. This powder was cautiously heated to 150 C0–200C0initially, and finally annealed at a range from 600 C0to 1000 C0for six hours.

The resulting product was submitted to a thermal analysis (TGA), which is a useful tool to explore a wide array of polymer properties. This research demonstrates the different applications of TA methods in the field of polymer-nanomaterial research and displays several examples of implementation of the differential scanning calorimeter (DSC). TGA was deployed to investigate the performance of thermal characteristics, which vary with the temperature, for the illustrations and structural characterisation, X-ray Diffraction (XRD) and analysis. A meticulous annealed temperature will output pure, single phase LCNFO / NP material with electrochemical behaviour. The powder was studied, and the dimensions of the cathode material were designed approximately for the XRD data using the Scherer’s equation. Furthermore, we used the Fourier transform for the IR (FT-IR) and surface morphology EDS and SEM analysis. The results focused on modifying the LiCoO2of the cathode materials by adding materials that are similar to Ni and Fe because these materials are documented as being their own state and not contaminated with the hexagonal geometry arrangement and R three m (gap assembly). We noticed that doped Fe has material that will perform better according to the capacity, power, rate capability stability and low cost, with increased storage capacity due to the nano-size effects.
The effect of adding graphene nanoparticles to the thermal performance of LiCo0.525Ni0.475O2cathode materials in Li-ion batteries
Authors: Al-Saedi Safaa I. , Naje Asama N. , Haider Adawiya J.
Published: November 2020

In this work, the effect of adding graphene to the performance of layered LiCo0.525Ni0.475O2(LCNO) cathode materials was investigated. Cathode materials LiCo0.525Ni0.475O2(LCNO) were prepared using a self-propagating combustion reaction. Graphene (G) was added to the prepared compound (LCNO) in different weight percentages to obtain LCNO/G (LCNOG) to improve cathode performance. The powder was divided into four parts weighing 10 g each, and the parts were mixed with percentages weighing 0, 0.5, 2, 4 and 6% of graphene with 200 ml of ethanol; they were then stirred several times at room temperature to dry completely The effect of graphene weight percentages on LCNOG mass loss was studied using thermo-gravimetric analysis (TGA). It was concluded that all of the added percentages of graphene behaved the same in all temperatures, except for 6% added graphene, where it demonstrated inverse behaviour at a high temperature. To determine the optimum annealing temperature range, TGA was identified at 650, 750 and 850 °C for 12 hours in the air. The X-ray diffraction (XRD) patterns of the LCNO and LCNOG showed the crystallisation of all powders in the space group R-3m and hexagonal axes for the crystal system. Energy dispersive spectrometry (EDS), field emission scanning electron microscopy (FE-SEM), a vibrating sample magnetometer (VSM) and atomic force microscopy (AFM) were also used. The LCNOG surface morphology consisted of regular coverage of nano-crystalline grains and random orientation.
High Uniformity Distribution of Fe@Au Preparation by a Micro-Emulsion Method
Authors: Al-Kinani Maha A. , Haider Adawiya J. , Al-Musawi Sharafaldin
Published: November 2020

In this study, the characterisation and composition of Fe@Au NPs were discussed. Au-coated Fe core-shell is a type of nanoparticle that contains a magnetic Fe NPs core with a fine layer of Au NPs synthesised by the micro-emulsion method. These Fe@Au NPs are characterised by Atomic Force Microscope (AFM), Scanning Electron Microscopy (SEM), High-Resolution Transmission Electron Microscopy (TEM) and UV-Visible Spectrophotometer. The best result and the smallest nanosize was obtained at a temperature of 38°C and HAuCl4.3H2O Volume 200mg. The size of Fe@Au NPs was 63.65 nm, the Fe NP’s core diameter was 32.47nm and the Au NP’s shell thickness was approximately 31.18 nm. Optimum results mention that temperature and the HAuCl4.3H2O volume play a great role in the formation of small, monodisperse Fe@Au NPs for future use as a drug delivery means to treat different types of cancer.
The Effect of the Nanoparticle SiO2 on the Mechanical and Physical Properties of Rubber Composites
Authors: Subeh Ahmed Abdulameer , Al-Maamori Mohammed H. , Hamzah Ahmed Fadhil
Published: November 2020

This paper investigates the effect of the nanoparticle SiO2 on the mechanical and physical properties of a rubber blend of natural rubber (NR) and styrene-butadiene rubber (SBR). The proportions of the nanoparticle that are added are 0, 0.2, 0.4, 0.8, 1, 1.5, 2, 2.5 and 3 pphr to a fixed percentage of rubber blend (30% NR/70% SBR), which has been prepared with vulcanisation factors, accelerators and activators using a two-roll mill laboratory, moulds and a thermal piston; the pressure, temperature and time difference test conditions according to standards. The results of the laborator tests show an increase in the mechanical properties (i.e. tensile strength, modulus of elasticity, resilience and tear resistance) with increases in the percentage load (pphr) until 0.8 pphr, which is when there is a slight decrease; the properties of hardness, fatigue and compression set also increase. While the results for the physical properties show an increase in viscosity, the greater torque, scorch and cure times decrease with increases in the proportion of SiO2 in the rubber recipe.