bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Specialty Natural Rubbers for Engine Mount Application
Authors: Kamaruddin S. , Ramly A. F. , Mohd Shukri N. , Bakri A. G. , Fourrier Q.
Published: August 2019

An engine mount secures the engine of a vehicle to its chassis. Successful application of elastomeric mounts as vehicle engine mounts has been observed over the years. Epoxidised Natural Rubber (ENR) and Deproteinised Natural Rubber (DPNR) are specialty rubbers with a potential for application in the development of engine mounts. In this study, a blend comprising natural rubber (NR) and polybutadiene rubber (BR) is used to produce the Original Equipment Manufacturer (OEM) part. Epoxidised Natural Rubber (ENR25 and ENR50) and Deproteinised Natural Rubber (DPNR) developed by Malaysian Rubber Board were used and compared with NR by evaluating both physical and mechanical properties of the rubbers with different filler loadings. The physical properties of NR exhibited excellent results opposed to other rubbers. However, a blend of ENR25 and BR reflected good compression set at 100°C for 96 hours. The performance of an engine mount comprising a blend of ENR50 and BR is promising in reference to the excellent mechanical properties over that of other rubbers. Dynamic stiffness and damping characteristics of the engine mount play an important role to achieve vibration isolation with acceptable engine motion control in a vehicle’s engine mount system. It is perceived that engine mounts produced with a blend of ENR50 and BR can improve vibration effects in dynamic conditions.
Rheological Properties of Carbon Black/Silica Hybrid Filler in Acrylonitrile Butadiene Rubber
Authors: Mohd Hasan MH , Kler JK , Ong SK , Manroshan S
Published: August 2019

Filler is a common additive added into rubber vulcanizate to achieve reinforcing performance. Typically, filler is compounded via two-roll mill which results in filler agglomeration and lower reinforcing efficiency. To gain higher reinforcing efficiency, filler agglomeration must be minimized via masterbatch preparation. This study investigates colloidal stability of carbon black/silica (CB/SiO2) hybrid filler and effectiveness between typical compounding and masterbatch process for NBR vulcanizate production. CB/SiO2 hybrid filler was fixed at 20 wt.% with ratios of 100/0, 75/25, 50/50, 25/75 and 0/100 were dispersed separately in sodium hydroxide (NaOH) via ball milling. The zeta potential, particle size and viscosity results showed CB and SiO2 dispersions stabilized after 48 hours of ball milling. NBR masterbatch with 50/50 ratio has highest flow resistance. SiO2 reinforced NBR masterbatch showed higher flow resistance compared to CB due to finer silica particle size. However, scorch and cure time for SiO2 reinforced NBR is slower than CB reinforced NBR as silica deactivate the accelerator. CB/SiO2 at 50/50 has highest Tmax and ΔT while 100/0 and 0/100 has insignificant differences. As conclusion, CB and SiO2 dispersions were stable based on zeta potential analysis and particle size reduced as ball milling time increased.
Frequency and Amplitude Dependence of Magnetorheological Elastomers Composites
Authors: Moksin N , Shuib R K , Ismail H , Harun M K
Published: August 2019

In this study, anisotropic and isotropic magnetorheological elastomers (MREs) based on nickel zinc ferrite and natural rubber were prepared. The amount of nickel zinc ferrite was varied at five different levels (20, 40, 60, 80, and 100 phr) to assess its optimum content for enhancing dynamic mechanical performance of MREs. Tan δ was measured through parallel plate rheometer over frequency range of 0.1-100 Hz and strain amplitude range of 0.1-6%. The results revealed that tan δ increased with increasing waste nickel zinc ferrite content and reached maximum value at 100 phr for both isotropic and anisotropic MREs. SEM micrograph showed that anisotropic MREs had chain-like columnar structures of magnetic particles in the matrix as a consequence of an applied magnetic field during curing. For frequency sweep test, tan δ for anisotropic MRE improved 244% and for strain amplitude test 159% improvement compared to isotropic MRE.
Evaluation of Impact Absorbing Properties of Thermoplastic Elastomers
Authors: Yajima N , Kawahara S , Matsuda A
Published: August 2019

The thermoplastic elastomers (TPEs) are physical mixtures of polymers. Impact absorbing materials in sports equipment are one of the expected applications of TPEs due to good process ability and less-smell. For examples, face guards, head-gears and protectors are expected to be applied. In this paper, static and dynamic mechanical properties of TPEs were investigated to expand the applicability of TPEs to the impact absorbing material for the sports equipment. In this study, TPEs developed by the Kuraray Plastics Co., Ltd. were applied for static and dynamic tests. To investigate the static mechanical properties of TPEs, the uniaxial tensile loading tests were conducted. The nonlinear viscoelasticity considering damage were applied to representation of the experimental results. The FEM analysis showed good applicability to static mechanical properties including damage which was excited by the maximum deformation. TPE. To investigate the dynamic mechanical properties of TPEs, a drop weight impact testing machine was developed. Impact absorbing properties of TPEs were evaluated by the impact force and impact time with baseball weight.
Study on Voxel Finite Element Analysis of Open-Cell Polyurethane Foam
Authors: Kimura Y , Kato K , Matsuda A
Published: August 2019

Establishment of a design method for the macroscopic stress-strain relationship of open-cell foam has been investigated because of the foam’s complicated microstructures. In this study, a material design method for the mechanical behavior of open-cell polyurethane foam using voxel finite element analysis is proposed to consider the microscopic structure and matrix properties. A finite-strain hyperelastic model was applied to a matrix of polyurethane foam. The Mooney-Rivlin model was adopted for the potential energy function of the hyperelastic model. To determine the mechanical properties of the matrix, original, solid specimens of polyurethane were prepared. The material parameters of the matrix were identified based on the tensile loading test results of the solid specimens. Microstructures of the open-cell polyurethane foam were determined using a CT-scanning system. Finite element models constrained by the original microstructural configurations were applied to numerical simulations. Periodic finite element models based on the modified microstructural configurations, the relative density of which was the same as that of the original models, were applied to the simulation. Based on the numerical results, verification of the design performance of the simulation code for open-cell polyurethane foam was performed. The simulation results were reasonably consistent with compression loading test results up to the plateau region.
Rubber Particles Coating Layer on Macroballoons and Its Physical and Compression Properties in Syntactic Foam
Authors: Anusha L , Zakaria Z , Chew KK
Published: August 2019

The effect of epoxy and acrylonitrile butadiene rubber (NBR) layers on physical and compression properties of macroballoons in syntactic foams was investigated. Epoxy mixture was used to coat on the surfaces of expended polystyrene (EPS) beads template, and the beads were cured to produced epoxy macroballoon (EM). The cured EM coat with NBR powders in order to form epoxy rubber macroballoon (ERM). Subsequently, the cured ERM was coated with epoxy mixture as the outermost layer on macroballoon to form epoxy rubber epoxy macroballoon (EREM). The EM, ERM, EREM were then filled into syntactic foam and post cured to ensure the shrinkage of EPS beads to produce hollow structures. Three syntactic foams with EM, ERM and EREM were characterized in terms of physical and compression properties, respectively. It was found that EREM exhibited the highest density and average wall thickness in syntactic foam. Overall, the inclusion of NBR powders as rubber coating of macroballoon with epoxy as the outermost layer resulted in improved compressive strength and toughness by absorbing energy with enhanced interfacial adhesion.
3-Dimensional Homogenization Finite Element Analysis of Foamed Rubber
Authors: Matsuda A , Oketani S
Published: August 2019

In this study, 3-dimensional homogeneous finite element analysis of a truncated octahedral unit cell which consisted of hyperelastic beams was conducted to predict macroscopic mechanical characteristics of the foam rubbers considering its microscopic structure. The homogenization theory was applied to finite element analysis code and the unit cells for simulation were assumed to have the periodic boundary condition. An original finite-strain homogenization FEM code for hyperelastic material and truncated octahedral unit cell were developed. The relative density of the homogenization analysis was adjusted by width of the beams in unit cell model. The rubber matrix was assumed to be represented by the nearly-incompressible hyperelasticity. The Mooney-Rivlin model and nearly-incompressible condition were applied to the hyperelasticity. The material parameters of the Mooney-Rivlin model for foamed rubber matrix were identified by the tensile loading test results. The developed code showed enough stability to predict the mechanical property of foamed rubber in the large strain region.
Ultra High Molecular Weight NORDEL™ EPDM for TPV and Low Hardness Molded Goods Enabled by Advanced Molecular Catalyst
Authors: Wu S. , Han T. , Thakur V. , Weeks R. , Li Pi Shan C. , Tuberquia J.
Published: August 2019

Ethylene propylene diene synthetic rubber (EPDM) is the material of choice to manufacture various automotive parts due to its natural stability and resistance to heat, UV, and ozone. In addition, its polyolefinic nature results in consistent processing and good filler and oil acceptance for use in compounds ranging from automotive weather sealing, under-the hood belts and coolant hoses, roofing membranes, gaskets and other general rubber articles. Building on a fifty-year history of performance, Dow’s Advanced Molecular Catalyst (AMC) and process technology advancements enable highly tailored design of EPDM molecular architecture including, composition, molecular weight and long chain branching (LCB). This is not only resulting in capacity efficiency and sustainable production but also increasing design options of the molecular features to tailor the performance for high in-use efficiency. This paper summarizes a new ultra high molecular weight (UHMW) NORDEL™ EPDM product and its potential applications. Case studies will be presented to showcase its use in thermoplastic vulcanizate (TPV), black color low hardness compounds, and lighter color (gray) washing machine gasket application. The EPDM polymer structure, compound formulation, mixing performance, compound rheology, vulcanization characteristics, and mechanical property improvements are discussed.
Oven Ageing versus UV Ageing Properties of Natural Rubber Cup Lump/EPDM Rubber Blend with Mangosteen Powder (MPP) as Natural Antioxidant
Authors: Rahmah M , Ahmad Khusyairi A R , Nur Khairunnisya H , Siti Nurbalqis M
Published: August 2019

Natural Rubber (NR) are susceptible to oxidation due to the presence of diene double bond. Improvement of NR properties can be enhanced by presence of antioxidant. Natural antioxidant can be a new source of additives to prevent and delay oxidation process. In this work, mangosteen powder (MPP) is exploited to be good potential additive in improving the aging properties of NR cup lump (NRCL) blended with EPDM rubber. Blended NRCL with EPDM rubber as a sealant had been studied with and without MPP. Aging effects upon thermal and weather exposure after two weeks had been analyzed by FTIR. Increasing amount of MPP had retained the diene bonds upon further rubber degradation. The broad band absorbance peak at 3410 cm−1 corresponds to O-H stretching with H-bond which indicates the existence of phenols in the MPP. Carboxylate groups and amine presence in MPP also found to exhibit absorbance peak at 1028 and 1608 cm−1 respectively. MPP contained polyphenol proven to be effective antioxidant agent in reducing degradation upon thermal and sunlight exposure. Oven and weathering tests performed for two weeks showed different aging behavior with weathering exposure found to have greater degradation effect due to radical attack by free radical from UV sunlight.
The potential use of immobilized Bacillus cereus ATCC 14579 for biodegradation of natural rubber latex film added with Metroxylon Sagu pith form
Authors: Adzami N.S , Azura A.R. , Tajarudin H.A.
Published: August 2019

The previous study reported that Bacillus cereus ATCC 14579 able to degrade natural rubber latex films added with Metroxylon Sagu pith waste form (MSPW/NR) and natural rubber (NR) latex films as main source of carbon and energy. Some attempts have been made to degrade them in the newly batch systems rather than disposing of them in landfill. Immobilization technique was performed to adsorb Bacillus cereus onto modified activated carbon. This work aims to study the potential of immobilized Bacillus cereus for biodegradation of MSPW/NR. The results revealed that 30% nitric acid for 2 hours impregnation time showed significant influence on Bacillus cereus adsorption. The highest adsorption capacity of Bacillus cereus was found to be 72.8% under its optimum conditions. The weight loss of MSPW/NR by 12.843 % were obtained after 14th days biodegradation period. Thus, immobilization of Bacillus cereus ATCC 14579 has potency to provide a biotechnological solution to the waste rubber and latex disposal problem.
Effect of Latex Compound Dwell Time for the Production of Prototyped Biodegradable Natural Rubber Latex Gloves
Authors: Rahman M F Ab , Rusli A , Kuwn M T , Azura A R
Published: August 2019

The production of prototyped biodegradable natural rubber (NR) latex gloves with the addition of sago starch as a fillers in latex compounding using Lab Scale Batch Dipping Machine has been investigated. As biodegradable gloves, the progress of biodegradation of NR latex gloves is also being determined through weight loss measurement test. Results showed the optimum dwell time of latex dipping was achieved at 6 sec with optimum tensile properties and within normal examination glove thickness. The weight loss of biodegradable NR latex gloves after one month soil burial showed additional of sago starch into latex compounding can accelerate the biodegradation process.
Studies on the Influence of Mixed Culture from Buried Soil Sample for Biodegradation of Sago Starch Filled Natural Rubber Latex Gloves
Authors: Rahman M F Ab , Rusli A , Adzami N S , Azura A R
Published: August 2019

The addition of sago starch into natural rubber (NR) latex compounds was aimed to accelerate the degradation process of the end products including gloves as an alternative to reduce solid waste disposal problem. In this research work, the degradation of sago starch filled natural rubber (SS/NR) latex gloves by a mixed culture from buried soil sample was investigated. The Gram staining test of mixed culture showed the Gram-negative bacteria are the dominant species as an effective bacterium to degrade the SS/NR latex gloves. The starch hydrolysis test was performed to confirm the existence of starch-degrading bacteria in mixed culture that consume sago starch from the gloves. Based on the biodegradation rate results obtained, the existence of starch-degrading bacteria together with rubber-degrading bacteria were observed, which accelerate the biodegradation of SS/NR latex gloves by 53.68%. Meanwhile, the biodegradation rate for sago starch unfilled natural rubber (control) latex gloves were only 50.31%. Thus, the addition of sago starch has shown an increased in the biodegradation rate, which can be used as alternative method to overcome the solid waste disposal problem.
Production of Poly(carbonate-co-ether) via Catalytic Polymerization of Epoxidized Linseed Oil, Propylene Oxide and Carbon Dioxide
Authors: Shaarani F W , Bou J J , Hakim R N
Published: August 2019

Poly-(carbonate-co-ether) was synthesized via catalytic polymerization between epoxidized linseed oil (ELO), propylene oxide (PO) and carbon dioxide (CO2) using heterogeneous catalyst namely Co-Zn double metal cyanide (Co-Zn DMC). The influence of polymerization time was studied. It was revealed that the properties of the resultant polymers were affected by the polymerization time. Within the range of polymerization time studied, the maximum average molecular weight (Mn) of the resultant polymer obtained was 6.21 × 105 g⋅mol−1 with polydispersity index (PDI) of 1.05 at reaction time of 24 hours.
Effect of Pyrolysis Temperature and Time on Properties of Palm Kernel Shell-Based Biochar
Authors: Mohd Hasan MH , Bachmann RT , Loh SK , Manroshan S , Ong SK
Published: August 2019

Pyrolysis is a thermal decomposition of biomass occurring in the absence of oxygen. Biochar (solid), bio-oil (liquid) and biogas (gas) are the typical products from pyrolysis of biomass. This endothermic process produced biochar with high carbon content. During pyrolysis, the material is heated up from ambient to a peak temperature and remains for a defined residence time. Therefore, the pyrolysis peak temperature and the residence time are the key parameters for pyrolysis. Studies on the effect of these parameters on the biochar characteristics and the pyrolysis products composition are numerous. However, there are limited findings of these parameters with palm kernel shell (PKS) as the biomass. This study focusses on the effect of the pyrolysis temperature and residence time of PKS on the yield of biochar produced and the biochar physio-chemical properties. The results showed that biochar yield decreased as the peak temperature and residence time increased. This finding is consistent with the findings by other researchers. However, those factors do not have distinct influence on biochar’s carbon content as found in other study which the peak temperature has the bigger impact instead of residence time. The effect of peak temperature or residence time on grindability; i.e. particle size of biochar after wet ball milled is insignificant. Smaller size of biochar may improve its function as reinforcing filler. As a conclusion, the optimum setup of pyrolysis is needed for a balance production in yield and biochar’s properties. It is recommended to produce biochar at higher peak temperature and shorter residence time to increase the total production. Additional analysis e.g. physical testing on the final polymer product can be used to investigate the effect of pyrolysis peak temperature and residence time.
Purification of Monomers Leads to High-Quality Lignin Macromonomers
Authors: Syed Azhar S.A.R. , Ahn Dong June
Published: August 2019

Purification is critical in any chemical process. The removal of impurities will produce the product in better quality and high standard. In this study, a new type of monomer was prepared by condensation polymerization of alkali lignin (AL) and methacryloyl chloride (MAC). The effect of AL/MAC ratio and the purification of MAC were investigated. The physical and chemical properties of the product obtained which is lignin methacrylate (LMA) were characterized by Fourier Transformed Infrared spectroscopy (FT-IR) and Nuclear Magnetic Resonance (1H-NMR). The result reveals that the purification was successfully removed the hydroxyl groups from the stabilizer in MAC and it is found that all the hydroxyl groups are coming from AL. The single interaction between AL and MAC has successfully enhanced the product obtain which does show no hydroxyl groups. The 1H-NMR data also showed that the purification of MAC influences the outcome. The noise and impurities were eliminated after the purification of MAC, and more pure products were obtained. This new monomer (LMA) synthesis that can be further utilized for various applications.
Numerical Simulation of the Reliability of In-Situ Eddy Current Testing Considering the Influence of Penetration Depth
Authors: Tian P Q , Zhan S Z , Feng Y W , Zhang X L , Xue X F
Published: August 2019

In order to study the reliability of in-situ eddy current testing, the factors affecting the in-situ eddy current detection and the signal response values are firstly determined. Then the numerical simulation model of eddy current detection is established by COMSOL, and the different values of the device and the tested structural are substituted into the simulation model to obtain the signal response value. Finally, the probability of detection (POD) curve is obtained by numerical simulation method based on function model. In this paper, based on the numerical simulation method of probability density function, the numerical simulation of eddy current testing reliability is formed. Through the in-situ eddy current testing reliability numerical simulation case, the detection probability of cracks in the structure is quantitatively affected by the penetration depth.
Identification of Key Conflict Nodes Based on Complex Network Theory
Authors: Jiawei Li , Xiangxi Wen , Libiao Zhang , Fei Liu
Published: August 2019

The current methods of detecting flight conflicts are difficult to grasp the overall conflict situation in the air, which is not conducive to the controllers to make accurate judgment on different conflict situations. In this paper, a method to identify key nodes of flight conflict based on complex network theory is proposed. Firstly, a conflict situation network model was built based on the ACAS protection area model. Then node degree centrality, closeness centrality and PageRank were used to evaluate the comprehensive importance of all nodes in the conflict situation network by AHP method. And we can find out the key conflict locations and conflict aircrafts based on the evaluation results of the index. The simulation results show that the model can effectively identify the key conflict aircrafts and positions in the airspace. And It can help controllers fully grasp the air security situation by classifing the air conflict situation levels.
Research on Height and Diameter of Doppler VHF Omnidirectional Beacon in Complex Environment
Authors: Fei Liang , Yue Hu , Yuankai Li
Published: August 2019

With the development of community around Doppler VHF omnidirectional beacon(DVOR), more and more DVORs are restricted, and even severely disabled. The DVOR’s counterpoise can be elevated to improve the coverage. But raising counterpoise will cause some problems such as null and worse bearing error. The paper research the lateral multipath, longitudinal multipath, height and diameter of counterpoise from the null, the first Fresnel zone, signal coverage, bearing error combing surrounding buildings and terrain, providing some technical means for improve or eliminate nulls and bearing error in construction of DVOR, and pre-evaluating whether it can pass the flight inspection after the completion of construction.
Long Time Integration for High Speed Target Detection Based on Radonkt-LVT
Authors: Chen Jie , Wu Qi , Zhang Yue , Chen Zengping
Published: August 2019

In this paper, a computationally efficient long-time integration and parameters estimation method via Keystone transform(KT), Radon Transform(RT) and Lv’s Transform(LVT) is proposed. Firstly, the KT-Radon is used to eliminate the range cell migration(RCM) of the echo after pulse compression, then using LVT to obtain the long-time integration and parameters estimation of high-speed target with acceleration motion. Compared with the GRFT algorithm, the proposed method only needs one dimensional search for range. Compared with the KT-FRFT algorithm, there is no need to search Doppler fold factor in this proposed method. So the proposed method doesn’t suffer from huge computation cost and obtain a good tradeoff between the computational cost and detection performance in comparison with the above algorithms. Finally, several experiments are provided to demonstrate the effectiveness of RadonKT -LVT.
A Fast and Collision Avoidance Distributed TDMA Schedule Based on the Multi-Arms Bandit
Authors: Zheng ChaoYi , Huang ShengChun , Li TaiLi
Published: August 2019

In this paper, we propose a novel distributed TDMA protocol based on the Multi-Arms Bandit model for the dynamic UAVs environment. Because of the frequent topology changes of UAVs, we consider a distributed communication protocol, which do not require the maintenance of accurate network topology information. Through the adaptive interaction between nodes, perceiving the surrounding topology environment and learning from historical experience, each node in the network can transmit information in a fast collision-free way. Also, the MAB model is utilized in our protocol, so that the time slot can obtain sufficient multiplexing rate through multiple rounds of node selection. Experiments show that the protocol can achieve better throughput and fast enough convergence speed, even in the case of high network density, and scales well with the size of the network.
A Modified KNN Indoor WiFi Localization Method With K-median Cluster
Authors: Lan Wei , Li Hongxin
Published: August 2019

Because of the serious attenuation and multi-path effect of GPS signal, outdoor-positioning technology can not be applied in complex indoor environment. Through the study of K-Nearest Neighbor applied in WiFi positioning, according to the problem that the time complexity of KNN algorithm increases linearly with the quantity of samples, this paper combined clustering algorithm with KNN optimized the similarity measure in fingerprint feature space and proposed a efficient indoor target location algorithm . Experimental results showed that the algorithm improved the positioning accuracy, had strong robustness to noise and more importantly, the positioning time was effectively shortened and it can meet the requirements of practical applications.
Electromagnetic Thermal Coupling Simulation Analysis of Silicon Carbide Shock Absorber
Authors: Xiaofang Yin , Xiaoning Liu , Jiayong Qin , Chunlin Du
Published: August 2019

This paper introduces a set of absorbing equipment used in 3.2GHz band vacuum high and low temperature environment. Through the finite element method modeling, COMSOL Multiphysics multi-physics simulation software analyzes the electromagnetic thermal coupling capability. The simulation results show that the absorbing properties of the silicon carbide pyramidal absorbing material are good. If the loss caused by the electrical conductivity of silicon carbide is considered, the absorbing performance of the silicon carbide pyramid will be greatly improved to -40dB. The simulation calculation model combines the electromagnetic field with the thermal, and gives the temperature curve and the isothermal contour dynamic diagram of the pyramid. It provides theoretical guidance for practical engineering applications.
Study on Sequent Test Effects of Atomic Oxygen/thermal Cycling
Authors: Zhai R Q , Tian D B , Jiang L X , Xia Y , Li X Y , Li Y
Published: August 2019

Two kinds of unidirectional laminates made from carbon/epoxy composite named M40/DFA-1 & M40/DFA-N3(nano TiO2 contained) are selected to study the different effects between different test sequences of atomic oxygen/thermal cycling. Based on the ground simulating test of atomic oxygen and thermal cycling, several kinds of tests and analysis are conducted, such as surface morphology observation, mass loss test, inter-laminar shear strength test, and X-ray photoelectron analysis of surface components. After the exposure of atomic oxygen and thermal cycling, surface erosions is observed on both of the materials, in addition, mechanical properties are both changed. It must be highlight that, under the condition of 1.5×1020 atoms/cm2 AO and 200 thermal cycles within the range of -150°C∼+150°C, different sequences lead to different results, either the extend or the tendency. In which, samples under AO+TC sequence exhibited relatively higher mass loss and erosion rate as well as more severe mechanical performance degradation.
Initialization Method of Nozzle Flow Field Based on One-Dimensional Isentropic Theory and the Study of Its Application
Authors: Zhao HaiLong , Peng Ke , Zhang WeiHua , Fan YuZhu , Jie JinLiang
Published: August 2019

The two-dimensional axisymmetric nozzle is initialized by two methods which are the hybrid initialization method of the commercial computational fluid dynamics software Fluent and the initialization program based on the one-dimensional isentropic theory. The first-order upwind format is combined with the SA model to solve the two-dimensional axisymmetric nozzle under the same boundary conditions. The convergence process is obtained in the process of numerical calculation, and the influence of two different initialization methods on the convergence process is analysed. The results show that the initialization method based on the one-dimensional isentropic theory effectively improves the convergence of the nozzle numerical model calculation process, accelerates the convergence speed and improves the calculation efficiency.
Research on Safety Risk Evolution of Military Aviation System Based on ANP-SD
Authors: Wang Qiang , Liu Qiuhan , Xia Ruicong , Huang Yingjie
Published: August 2019

With the development of equipment, the complexity of China’s military aviation system continues to increase. The system risk is transformed from the initial independent risk factor to the cross-influence risk factor, which makes the system risk control difficult. In order to maintain the safety level of military aviation system, the factors affecting the safety level of the system are analysed from five aspects: personnel, machine, environment, management and logistics. The analytic hierarchy process (ANP) is used to construct the model of the system risk factors and the system dynamics method is used to establish the risk evolution simulation model, and quantitatively analyse the sensitivity of risk factors to explore the basic rule of risk evolution.
Application of Fault Diagnosis Expert System for Unmanned Vehicle Safety
Authors: Chen ChunPing , Zhang Lin , Wang Jie , Zhang Jie
Published: August 2019

In order to ensure the safety of the underwater unmanned vehicle (UUV) and reduce the risk of damage or loss during operation, the safety system will be equipped on the UUV. It can accurately locate the fault when the submersible encounters dangerous situations, such as equipment failure and cabin flooding, assess the dangerous situation and make emergency measures, so as to help the underwater unmanned submersible realize self-rescue. Fault diagnosis expert system is a knowledge-based fault diagnosis method, which is suitable for complex systems with incomplete knowledge. However, because the working environment of the underwater unmanned underwater vehicle is very complex and the fault types are diverse and change in real time, the traditional fault diagnosis expert system may not meet the response time requirements of the safety system due to the long response time required. Therefore, the finite state machine technology is applied to the diagnostic expert system to improve the response speed of the diagnostic expert system, and at the same time make the system more flexible and convenient to expand its functions. In addition, the model-based design method was applied to establish the model of the security system in stateflow, and the model verification was carried out. With the help of PLC Coder tool, the code of the target controller was generated and the algorithm was deployed.
Structural Design and Difficulties of Solar UAV
Authors: Zhang W W , Zhang L G , Yan Z W , Wang L
Published: August 2019

The design of high-altitude and long-endurance solar aircraft is obviously different from that of conventional aircraft. Its unique energy system and operating conditions make it necessary to carefully weigh the key technical details in design. The structure has a great influence on the endurance performance of solar aircraft. The structure weight can be roughly estimated by the proportion of the airborne energy system to the total weight of the aircraft, so as to optimize the structure. Through the analysis of several typical solar aircraft, it can be concluded that the aerodynamic layout and structure design have a great impact on the flight time and performance of solar aircraft. Finally, the challenges faced by solar aircraft are presented, which can provide reference for the design of solar aircraft in the future and help.
Research on the Variation Analysis Model for CFRP Assembly
Authors: Yu Jianfeng , Huang Shuhan , Zhang He
Published: August 2019

The conventional error analysis model is based on Key Characteristics (KC) tree [1] and the nominal 3D assembly model. Before the actual execution of assembly process, the potential interferences and out-of-tolerance problems are simulated and predicted. Then the tolerance and assembly schemes of the parts are optimized accordingly. This method requires statistical deviation data of parts and it can only give a rough probability for mass production case. In this paper, the common CAT technologies, variation analysis and optimization method are presented with an example of wing box model in 3DCS. Based on KC tree and optimizing theories a model analysis method is proposed to improve the performance in the case of multi-material part assembly processes.
Human Interface Research of Civil Aircraft Cockpit Based on Touch Control Technology
Authors: Yang Wen , Sun Qin , Gao Xiaolong , Dong Dayong , Ma Xianchao
Published: August 2019

Touch screen technology is an important direction of the aircraft cockpit technology development. More and more touch screen test units are applied in the cockpit. However, most of the touch screen interface design is only a simple copy of the physical interface, which does not bring any benefits to the aircraft, but will cause some safety effects. Fundamentally speaking, these test units did not consider the impacts of flight crew operating procedures, human factors, flight scenes, and other factors on touch screen technology. This paper gives some advantages and disadvantages analysis for the touch control technology and provides a new concept of cockpit overhead control panel based on the touch control technology. The overhead touch control panel can not only effectively reduce the workload of the pilot, reduce the weight of the system, but also ensure the same flight safety with the physical panel. Keywords. Touch Control, Human Factor, Workload, Hybrid Layout, Ergonomics Evaluation.
A CAS Message Simulation Module Used in Civil Aircraft for Air Management System Failure Diagnosis
Authors: Haiyan Xi
Published: August 2019

Air management system is one of the most important airborne systems on civil aircraft, which is responsible for controlling aircraft bleed air, cabin pressure control, wing anti-icing, cabin ventilation and temperature control. And the air management control system is the brain and neural network of the entire air management system. The air management control system control the various subsystems of the air management system and control the air management system to work together with other interfaced systems. Air management system control logic and interface signals are the key points and most difficulty parts in air management system control. For this highly complex system, failure diagnosis is most important and difficult part in ground test and flight test. Usually faults are reflected on the CAS message and synoptic pages as the alarms. However, the causes of such alarms may be varied. The traditional trouble shooting approach is to check the control specification documents which are complicated and hard to find the root cause. If there is a CAS message simulation module database that can be quickly traced back to the trigger logic of any one of the alarms, and the signal relationship between the alarms is displayed, the control logic of the system is clearly displayed, the failure diagnosis would became simple and intuitive. Based on the above design intention with referring to control specification, this paper created a set of air management system alarm models by using Matlab/Simulink. These alarm models are used for system troubleshooting and design’s optimization. Finally, an application of cabin pressure control alarm with both trouble shooting and optimization is introduced.
Corrosion Detection for Large Steel Structure base on UAV Integrated with Image Processing System
Authors: Chen Qingcheng , Wen Xiang , Lu Shujie , Sun Dongxiao
Published: August 2019

Large cranes and other outdoor large steel structures need to be checked regularly to ensure their safety, and corrosion detection is one of the most important inspection item. Traditional manual inspection has many disadvantages including high labour intensity, low efficiency and low detection accuracy. In this paper, a novel corrosion detection method based on UAV intelligent image recognition is proposed. The six-rotor UAV can collect the photos of the steel structure device safely and reliably. With the intelligent corrosion recognition algorithm proposed in this paper, infection such as background noise can be eliminated, and the corrosion area in the image can be identified automatically with high precision. A test device has been built and the results show that the device and method can identify the corrosion area effectively.
Mechanism and Characteristics of High-Frequency Pulsed Jet Circulation Control
Authors: Zhan Ren , Zhang Deng-cheng , Zhang Yan-hua , Zheng Wu-ji , Li Yi-wen
Published: August 2019

Conventional circulation control technology presents problems in certain situations. Pulsed jet circulation control appears to be a feasible alternative to solve such problems, especially for the high-frequency pulsed jet (HFPJ). To acquire the aerodynamic characteristics of the HFPJ and reveal the mechanism behind it, numerical simulation is conducted using a verified computational fluid dynamics (CFD) method. The action mode of the pulsed jet characterized by equilibrium and oscillation is proposed according to the analysis of a dynamic procedure. Lift and drag characteristics are obtained, defining the critical frequency to demarcate high and low frequencies. An oscillation function is also established to illustrate the difference between the characteristics of the HFPJ and a low-frequency pulsed jet (LFPJ) by analyzing the simulation results. The pressure distribution and flow field in the simulation results explain the stall characteristic of the HFPJ. Series results indicate the HFPJ demonstrates superior lift augmentation and drag reduction compared to the LFPJ and steady jets.
Mission Capability Assessment of 3D Printing Cubesats
Authors: Chen Zhiyong , Zosimovych Nickolay
Published: August 2019

With the successful development of integrated technologies, many spacecraft subsystems have been continuously miniaturized, and CubeSats have gradually become the main executors of space science exploration missions. It is a new challenge to combine the CubeSat design with 3D printing. Compared with traditional manufacturing through machining, 3D printing technology has several advantages including short period of manufacturing, high accuracy in manufacturing small parts and low cost. The research task of this paper is a LEO (Low Earth Orbit) CubeSat mission, with a maximum acceleration of 5 g during the launch process, the internal operating temperature range of the CubeSat is from 0 to 40 °C, external temperature from -80 to 100 °C. The environmental factors were fully considered in the CubeSat design process, the impact load received during the CubeSat launch process and the working environment after reaching orbit were simulated and analyzed by ANSYS after the design parameters were obtained to verify the feasibility of the design.
Stability Area of a Spacecraft’s Partially Invariant Centre of Mass Motion Stabilization System
Authors: Zosimovych Nickolay
Published: August 2019

In practice, a spacecraft’s stabilization system, which is partially invariant to the disturbing moment, is the easiest to implement. The velocity performance limitation of the control actuator has the most influence upon stability of the system among all the nonlinearities considered in the mathematical modelling. Therefore, we shall consider a model of an invariant stabilization system with due regard to nonlinearity. For the system under consideration, it is possible to construct lines of equal values of the auto oscillation amplitude in a two-parameter plane. The study of the stability of the proposed partially invariant stabilization system revealed that it is possible to ensure sufficient stability margins in the system under consideration by choosing parameters for the stabilization controller. At the same time, it allows to provide high quality of the transition process.
Study on the Effects of Atmospheric Parameters on Space Vehicle Design
Authors: Peng-fei Guo , Fei Wang-hua , Xiao Cun-ying
Published: August 2019

For the space vehicle flying in the airspace and near-space, the structure safety and attitude control ability are related to the surrounding atmosphere. The distribution characteristics of atmospheric parameters, including temperature, pressure, density and wind field should be studied based on the data statistics. In this article, the spatiotemporal distribution characteristics and measurement methods of atmospheric parameters are summarized, and the effects of atmospheric parameters on the engineering design of ballistic trajectory, propulsion system, aero-thermal heating, and attitude control system are provided. These results have considerable significance in the space vehicle general design.
Review on the Development of Satellite Formation and Collision Avoidance Technology
Authors: Hongqiang Sun , Zhanyue Zhang , Yiwen Hu
Published: August 2019

Formation satellites have a very broad application prospect in many aspects due to the characteristics of unlimited baselines, multi-satellites cooperative working, flexible control and strong survivability, such as distributed radar, electronic reconnaissance, three-dimensional imaging, regional navigation and positioning. In the aspect of avoiding space debris collision, the maneuvering avoidance for a single satellite is often adopted, but there are few studies on the coordinated avoidance of formation satellites. This paper introduces the concept and research status of formation satellites, and lists the common formation satellites in the world, then introduces collision warning technologies and collision geometry relation determination of formation satellites, including BOX regional warning method and collision probability warning method. In addition, the strategies of satellite evasive maneuvering are analysed, and various maneuver strategies on different purposes are introduced. Finally, analysing and comparing the research status on debris collision avoidance of formation satellites, a method to keep the working efficiency of formation satellites while maneuvering is put forward.
Assembly Method for Satellite Propulsion System based on HoloLens
Authors: Zhang Wei , Zhang Jie , Chen Huajun , Zhang Bin , Liu Feng , Zhao Jun
Published: August 2019

As the satellite design changes from the traditional 2D mode to the 3D digital mode, the satellite assembly also enters the 3D assembly mode. An effective and accurate propulsion system assembly information transmission method from designers to operators is not formed, in the process of complex propulsion assembly, operators need to frequently confirm status back and forth between satellite and computer stations, and accidents with incorrect polarity in component installation often occur. In order to improve efficiency and quality of satellite propulsion system installation, a system based on HoloLens is designed. The successful application of this system provides a new solution for satellite propulsion system installation and marks a new step in the digital assembly capacity.
Adaptive Backstepping Sliding Mode Fault Tolerant Control for Satellite Attitude under Actuator Faults
Authors: Huo Junhai , Meng Tao , Jin Zhonghe
Published: August 2019

Modern spacecraft missions place stringent performance requirements on the reliability and stability of spacecraft attitude control system. However, during long-term in-orbit mission, actuators may suffer faults. In this paper, we proposed an adaptive fault tolerant control law for attitude control under actuator failures and external disturbances. Firstly, the attitude dynamic model under actuator faults and attitude kinematics are described. Then, in order to solve the attitude control problem under actuator faults and external disturbances, an adaptive backstepping sliding mode fault tolerant control scheme is designed. According to Lyapunov theory, the closed-loop system is proved to be globally asymptotically stable. Finally, the numerical simulation results demonstrate that the proposed adaptive controller can achieve anticipative attitude control performance, fault information estimation and well fault-tolerant capability.
Use of Tetrahedral Finite Element Method for Computing the Gravitation of Irregular-Shaped Asteroid
Authors: Yin Weidong , Shu Leizheng , Yu Yang , Gao Yang
Published: August 2019

Asteroids are one of the most important targets for deep space exploration. In previous asteroid missions, the accurate estimate of gravity has proved to have a strong influence on the design of the approach orbit and navigation strategy. The wield gravitational field of an asteroid is mainly caused by the irregular overall shape and possible heterogenous mass distribution the interior. We propose to use the finite element method to compute the gravity of irregularly shaped asteroids; this method combines the advantages of the conventional mascon method and the polyhedral method. The tetrahedral meshes can be generated following the conventional division technique. Taking asteroid 216 Kleopatra as an example, we calculate the exterior gravitational field using the above mentioned methodology. We then compare the results from the finite element method and the polyhedral method under a degenerated case, i.e., with constant density. Then, four different density distribution assumptions are given, and the gravitational fields are calculated respectively. The comparative study and the density distribution assumptions indicate that the proposed method is suitable for modeling an arbitrary asteroid with nonuniform mass distribution. This method is expected to provide reliable gravity data for the design of guidance, navigation, and control systems in future asteroid missions.
Deep Neural Networks Based Real-time Optimal Control for Lunar Landing
Authors: Zhu Lingchao , Ma Jian , Wang Shuquan
Published: August 2019

Recent research on deep learning control, a new control algorithm based on machine learning able to learn deep architectures, has shown excellent performance on robots and drones. With the development of intelligent control like deep learning and reinforcement learning, accuracy, real-time, adaptability, robustness and autonomy of control algorithm have been achieved by the intelligent controls. Traditional control methods have difficulties to achieve nice performance in complex situations. Deep learning offers powerful algorithms to real-time search near-optimal controllers of lunar landing spacecraft with nonlinear dynamics. In terms of lunar landing control system, deep architectures offer the possibility to get an approximate solution of co-state equation without time-consuming iterative process. Furthermore, real-time optimal thrust during lunar landing may be derived directly through deep neural networks. As a single infrastructure for machine learning in both production and research, TensorFlow is chosen for training the deep artificial neural networks in this paper. Numerical simulations demonstrate the effectiveness of deep neural networks. The results of deep neural networks based optimal control are contrasted with traditional optimal algorithm, whose main idea is to track the pre-designed optimal trajectory by ground station. This research provides an effective approach to cope with the lunar landing problem.