bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Energy Reduction Techniques in STT-RAM
Authors: Durga Eswar Vura Sai , Devi Bhavani K , Nandan Durgesh
Published: January 2021

Spin Transfer Torque Random Access Memory (STT-RAM) is suitable to be considered for cosmic memory. In STT-RAM the altercative period of attractive burrowing intersection is exchanged by the showing up of turn enraptured current over the intersection and it appear to be the most preparing elective with the more thickness and low introduction power, one of the major test for STT-RAM is the more write current, this paper proposes dual source write assist circuit method to reduce the equal compose vitality that prompts a diminishing in power utilization and the limit voltage of dynamic transistor to rising temperature. The MTJ temperature will increase than the write error rate is reduced. The final result is by effective use of VDD and threshold voltage values the write energy will be reduced. Right now, results utilizing a CMOS 65-nm get to transistor and the 40-nm MTJ innovation affirm that the projected compose help strategy prompts 81% of robustness is spared and its further incorporates just 9.6% territory excess to a 16-kb of STT-RAM cluster. And furthermore, another compose help technique is proposed to the end the compose activity in the wake of exchanging happens in the attractive burrowing intersection (MTJ), thus the both compose time vitality utilization of 1T-1MTJ piece cells will create.
Study on Power Minimization techniques in SAR ADC Devices by Using Comparators Circuits
Authors: Divya Sree P. , Jyothsna Raj B. , Srinivas B.
Published: January 2021

Comparators play an important role in designing of SAR ADC. In this paper we achieve the required performance of SAR ADC at minimum power usage. Using of comparators will reduce the power and noise, Dynamic latch circuit used in comparator increases the speed. The differential amplifier is also discussed. Here we will get to know about Ramp ADC and also about various DAC’s like M-DAC and AUX-DAC. The time-interleaving technique is the design technique that is used to increase the speed.
Common Vulnerabilities Exposed in VPN – A Survey
Authors: Bansode Rama , Girdhar Anup
Published: January 2021

In COVID-19 Pandemic, Internet traffic has been increased by up to 90%. Work- from-home culture is initiated by almost every organization. The technology adapted to access the Enterprises Intranet is VPN (Virtual Private Network). Infrastructure administrators implemented/updated VPN with the latest versions along with the security scripts to access Intranet. However, the contingencies faced by the organizations are out of their scope. Now VPN security is a big challenge for almost every organization. The Veracity is that no one claims the full prove security system in their Infrastructures. The latest Vulnerabilities have been exposed and indexed in context to VPN Hardware’s/Software’s/Configurations and Implementations. In this paper, it has been decided to analyze the exposed VPN vulnerabilities, along with the ongoing issues which have not been listed to date through the survey. The mitigation policies have been proposed based on observations.
Cognitive OFDM-NOMA System: A succinct Study
Authors: Vamsi Krishna Chavatapalli Tarun , Deepika Chandana Mani , Saranya B.S. , Neeladri Murrey
Published: January 2021

Integration of non-orthogonal and orthogonal multiplexing used to enhance the capacity of the system is presented here. This is also called as cognitive OFDM- NOMA. Here we overcome some problems which are divided into sub problems i.e., the power allocation optimization, user scheduling and sensing duration, respectively. Orthogonal frequency division multiplexing (OFDM) for multiusers can also be done by clustering based radio allocation (RA) scheme. This will improve maximum usage of wireless communications by optimizing the sum capacity of secondary users. The users in same group have the same OFDM sub channels to enhance spectrum utilization. Mobile networks have used time/frequency/code domain for multiple access, while in NOMA the power domain will be used.
A Review on Image Processing Sensor
Authors: RadhaKrishna M.V.V. , Venkata Govindh M. , Krishna Veni P.
Published: January 2021

Image sensors are used in all digital cameras, mobile phones and all other devices where images are to be captured. The most common parameter used by consumers to compare the different cameras is the pixel array size which is usually given in Mega pixels. The image quality is better with a higher megapixel count. Another parameter to distinguish between the different cameras is the type of imaging technology used like CMOS (Complementary metal oxide semiconductor) or CCD (Charge coupled devices). In this review we will present the working principles of an image sensor and conversion of light to electrical signals and subsequently to an image. The functional differences between the CCD and CMOS sensors will also be presented.
Detailed kinetic modeling of nitroglycerin low-temperature decomposition
Authors: Glorian J , Baschung B
Published: January 2021

Nitroglycerin (NG) is mostly used as an ingredient in double-base propellant formulations. In this study, a first automatically generated detailed kinetic model of NG decomposition has been developed. The construction of this model was made possible by performing computations with the open source software package Reaction Mechanism Generator (RMG). To enable a faster convergence, significant intermediate species of NG decomposition and optimized operating conditions were indicated in the RMG input parameters. Thermochemical data related to the significant NG decomposition species were derived from ab initio calculations at the B3LYP 6-31G(d, p) level of theory. To validate the RMG-built mechanism, simulations were performed with CHEMKIN-Pro. Computed species profiles from simulations were compared with flash pyrolysis measurements from the literature. Sensitivity analysis were performed and the most important elementary reactions were identified. Some rate constants were slightly adjusted to improve the predictivity of the model. The model is able to predict the species concentration profile of the main pyrolysis products. Although experimental data are scares, this automated kinetic generation approach, applied to energetic materials, seems to be highly promising.
Self-propagating combustion simulation of sputter-deposited nano-energetic multilayer films
Authors: Shi Anran , Zhang Wei , Shen Ruiqi
Published: January 2021

There are dependences of reactivity of nano reactivity multilayer films on scale, and the chemical pre-reactions at interface of reactivity multilayer films (RFMs) are avoided. The reactivity of Al/Ni, Al/Ti nano RFMs were analyzed by XRD and DSC. Analyzed results shown that the released heat of nRFMs depend on thickness of reactant layers, the thinner layer, the less released heat and the released heat is less than its theoretical heat. A pre-reaction region exists possibly at the interface of boundary layers by XRD analysis. A simple equation is derived to calculate the thickness of pre-reaction by the experimental data of RFMs reaction heat. The calculated results shown the thickness of pre-reaction layer depends on increasing of scale progressively.
Combustion performance with ap and boron addition in staged hybrid rocket
Authors: Lee Changjin
Published: January 2021

This study investigated the effect of ammonium perchlorate (AP) and boron addition on controllability of the combustion temperature in fuel-rich effluent and system specific impulse. In addition, a series of combustion tests was carried out to analyse and evaluate the effect of boron addition on fuel regression rate and radial temperature profiles. To keep the hybrid rocket engine advantages, upper limit of AP and boron contents in solid fuel was set to be 15 and 10wt% respectively. The results suggested that AP addition proved to be very effective in controlling the effluent temperature. Not only that, it also offers less injected oxidizer mass flow, and resulted in less O/F variation, and less combustion pressure while producing the same combustion in temperature fuel-rich effluent. With boron addition, it also provided more uniform radial temperature distribution. Also, boron addition increased specific impulse by 6.8-13.7%. Secondary combustion using different solid fuels showed a decrease in c* efficiency with increasing boron content in solid fuel. Combustor length and combustion pressure were introduced to improve the combustion of boron particles, however, combustion efficiency was decreased with increasing combustion pressure and combustor length for given test conditions.
Advances in Disruptive Technologies of Ultrahigh-energetic Materials
Authors: Guiyu Zeng , Xiufang Qi , xiaobo Liu , Xi Zeng
Published: January 2021

Since this century, disruptive innovating technology has developed rapidly and become a significant power of promoting science & technology development and military change, it will also affect energetic materials’ development profoundly. In order to realize the impact of disruptive technologies on energetic materials’ development, based on tracking the disruptive technology progress of energetic materials field at home and abroad, the disruptive technologies of ultrahigh-energetic materials has been reviewed, and the technological trends of metal hydrogen, all-nitrogen compounds, material genome and nuclear-energy are mainly analyzed, these disruptive technologies will greatly promote the innovative development of ultrahigh-energetic materials.
Numerical simulation on explosion shock wave overpressure produced by double charges
Authors: Qiu J L , Wang Sh Y , Jiang J W , Li M , Men J B
Published: January 2021

The influence of the number and spatial layout of charge on the overpressure was studied using numerical simulation. The 2-D axisymmetric models were established, considering that the pressure-time history of two equal-intensity shock waves is equivalent to that of shock waves reflected from a rigid surface. At the same position, the overpressures produced by single charge and double charges, which were installed with different included angles, were measured respectively. The results show that the overpressure produced by double charges increase significantly compared to that produced by single charge. With the increase of the included angle between double charges, the overpressure increases and reaches the maximum value when the included angle is 180°.
Effects of shell thickness on the fragment velocity distribution of D-shaped casing filled with explosive
Authors: Guo Zhiwei , Huang Guangyan , Liu Han , Zhang Peng , Feng Shunshan
Published: January 2021

Asymmetric casings filled with explosive have attracted increasing attention in the defence technology (e.g. innovative warhead design) and improvised explosive devices (IEDs) protection. As a typical asymmetric casing, D-shaped casing has been used in deformable aimable warhead, deployable aimable warhead as well as warhead in hypersonic weapons. To assist the design of asymmetric warhead, this work examined the velocity distribution of fragments from the bottom part of the D-shaped casing with different shell thickness. The fragment velocity distributions of the D-shaped casings with different shell thickness were numerically analyzed based on the SPH method. Numerical and theoretical analysis showed that there are opportunities to do optimization of shell thickness of D-shaped casings to maximum the utilization of the energy released by explosive. The findings herein could serve as a reference for further investigations on the fragment velocity distribution of D-shaped casings and provide a foundation for asymmetric warhead design.
Research on drop tower technology for simulating explosive impact load
Authors: Zhou Y B , Zhang M , Luo M , Wang X H , Sun X W , Liu Zh
Published: January 2021

When military vehicles are subjected to a mine blast, the vehicles will be damaged and the occupants will be injured. The main objective of this paper is to study the feasibility and accuracy of the drop tower to simulate the response of the vehicle body under the actual explosion condition. The equivalent damage method of impact waveform simulation was studied, and the feasibility of the equivalent damage principle of impact waveform based on change in velocity was verified. By analyzing a large number of data of simplified seat impact simulation, the mechanical model of the drop tower was analyzed. Through the correlation study of the parameters of the drop impact load, the relation formula of the drop height required by the target load was constructed, and the customization of the impact load was realized. The response simulation of the protective seat in the explosion was completed in the drop tower, which verifies the accuracy of the drop tower in simulating the explosion impact load. In addition, the results provide a good basis for the follow-up research.
Flight characteristics and mutual interference analysis of projectile launched in parallel
Authors: Zhu W F , Zhao N , Qu J , Wang Y W
Published: January 2021

Using the knowledge of computational fluid dynamics, a 3D simulation model of a 16 tube gun was established, and the process of muzzle flow field from single formation to mutual interference, stability and attenuation was simulated by solving N-S equations. Through the simulation analysis, it can be seen that the muzzle flow field formed by each barrel will influence and superpose each other when the multi-barrel gun is launched, and the lateral force caused by the asymmetric muzzle blast wave is acted on the projectile, and the lateral force of the middle four projectiles is small, the other 12 projectiles is larger. The results can be used as a reference for structural design, firing accuracy prediction and muzzle parameters test of multi-barrel launching weapon system.
Study on theoretical calculation of quasi-static pressure for aluminized explosive in confined space
Authors: Fan Xiao , Zhang Liansheng , Wang Xin
Published: January 2021

The process of the explosion damage in confined space mainly involves two parts, shock wave pressure effect and quasi-static pressure effect. A complicated afterburning reaction occurs in the internal explosion of aluminized explosives, not only enhancing the intensity of the shock wave, but also having a great influence on the final quasi-static pressure. A theoretical calculation model of final quasi-static pressure for aluminized explosive in confined space considering afterburning effect was proposed, based on the analysis of chemical reaction, the law of conservation of energy and the improved Jones-Wilkins-Lee equation of state. The factor that the volume of gaseous explosive products decreases in the afterburning reaction was also taken into consideration. The results of RDX-based and HMX-based charges calculated by the model were then analyzed and compared with the references’ experimental results as well as Anderson’s empirical formulas’ to verify the reliability and correctness of the proposed model. The results show that: the final quasi-static pressure of aluminized explosive calculated by the theoretical calculation model is in good agreement with the results of experimental measurement in the papers and the relative error doesn’t exceed 10%; the Anderson’s empirical formula is inapplicable to predict the final quasi-static pressure of the aluminized explosive in confined space. The study in this paper can provide a better theoretical calculation model to predict the final quasi-static pressure of aluminized explosives and provide some reference and guidance for the assessment of internal explosion damage of aluminized explosive and the design of explosive-resistant structures.
Research and engineering by REC “Mechanobr-technika” of additive technologies
Authors: Cherkasova M V , Samukov A D , Dmitriev S V , Mezenin A O
Published: January 2021

Demand for additive technologies and necessity for high-quality metal powders are growed. The results of technological research of finely dispersed powders was explored. This finely dispersed powders was gotten by vibration effects to produce conditioned commercial products that meet the requirements of additive technologies. This product can be used in powder metallurgy, mechanical engineering, processing metal waste. Research is observed of application of grinding metal waste from metal processing using the example of nickel cutting and the subsequent production of metal powders.
3D Printing and Characterization of Metamaterial Composite Structures for Absorbing and Shielding Electromagnetic Waves
Authors: Yin Lixian , Tian Xiaoyong
Published: January 2021

Electromagnetic (EM) absorbing and shielding materials possess critical position in defence field. However, traditional absorbing materials failed to achieve a wide absorption band because of the impedance mismatching between absorbing materials and air. And Traditional shielding materials, such as metals, failed to meet the increasing critical needs because of the large density, low corrosion resistance, difficulty in fabrication of complex structures. To solve these problems, a metamaterial composite structures with good performance on EM absorbing and shielding was proposed. The composite structure consists of a metamaterial absorber and a composite shielding structure. The metamaterial absorber is composed of graphene composite metamaterial whose impedance is gradually increased by tailoring the geometric parameter and graphene content. The shielding structure was prepared by continuous carbon fiber (CCF) reinforced composite. The composite structure was fabricated by multi-process 3D printing technology, with which different composites can be fabricated integrally without assembly. Experimental results showed that the absorption bandwidth of the composite structure was 32 GHz (4.5∼14.5 GHz, 17∼39 GHz), and the shielding effectiveness was larger than 63 dB. The excellent absorbing and shielding performance indicates that the composite holds great potentials in defense and that the design and fabrication method is useful for improving the defence survive ability in complex EM environment and fabricating EM functional structures cheaply, rapidly and facilely.
4D printing for continuous fibers reinforced composites
Authors: Wang Q R , Tian X Y
Published: January 2021

4D printing structure can be applied to the truss or the solar sail of spacecraft. At present, most 4D printing structures often have poor structural stiffness and deformation accuracy. In this study, a 4D printing process based on the composites with embedded continuous fibers is proposed. Due to the different thermal expansion coefficient and elastic modulus of fiber and resin, the structure will produce bending deformation when the temperature changes. The influence of fiber trajectories on deformation curvature is calculated and simulated, and then, some complex structures have been prepared by 4D printing process. The 4D printing structure of continuous fiber composite has better mechanical properties and higher deformation accuracy.
Design and Research of 2000T Wide Plate Tensile Testing Machine
Authors: Chen K Q , Zhang X G , Zhang L , Gu P , Zhang H W , Liu Ch
Published: January 2021

Wide plate, wide plate weld, pipeline girth weld and plate welded of panel used to the storage tank were wholly stretched by 2000T wide plate tensile test machine when using the related fixture. Tensile strength, initiation crack position of the joint crack, tolerance of the existing defects of welded joint, possibility of the crack propagation and fracture were studied. Their weak links were found, the formation of defects were avoided by welding technology and technical means. The closed loop control was realized by using advanced servo valve and high performance measure and control system, computer technology was used fully, multifunctional test control of the machine was realized. A number of servo cylinder precise synchronous control loading mechanism was adopted by 2000 T wide plate tensile testing machine, the design of its loading mode, servo cylinder, sensor installation layout and combined structure of super power sensor was the first in China, which created a platform for the development of large structure testing machine in the future.
High precision machining device for large-scale key parts of aluminum alloy
Authors: Chen H H , Meng F J , Zhang D S , Guo H B , Sang M , Qian D M
Published: January 2021

A high precision machining device for large scale curve groove of aluminum alloy key parts has been developed, the device is composed of a workpiece spindle drive system, a lathe bed, a hydraulic clamp system, a cutter spindle drive system, a deep feed shaft drive system, a linear feed shaft drive system, a data acquisition feedback system and a numerical control system, it improves the manufacturing precision and the whole strength and rigidity of the curve groove of the large aluminum alloy key parts, especially can be used for the whole precision machining of the curve groove of the high strength and high rigidity aluminum alloy key parts, and reduces the production cycle and cost, the key technical problems of cutting tool deformation and vibration control in NC milling and grinding wheel wear and correction in NC grinding are solved, it can meet the requirements of high-strength, high-rigidity and high-precision machining of large-scale aluminum alloy key parts.
The technology development direction analysis of the small portable unmanned ground platform
Authors: Liu X J , Su B , Yao Y A , Liu CH , Zhou L
Published: January 2021

The small portable unmanned ground platform, with its small size, small quality and diversity of mobile configuration, meets the functional requirements of individual soldiers carrying narrow space reconnaissance and detection tasks. As an effective complement to unmanned aerial vehicle and large unmanned platform, it becomes the end of execution of unmanned combat system, and plays an important role in promoting individual combat capability and improving the construction of unmanned combat system. In this paper, through the application of demand, the unmanned platform mission environment, development trend and key technology analysis to sort out the development platform to build micro unmanned technology framework for the subsequent step by step development of micro unmanned platform technology to provide technical support.
Design and Implementation of Trajectory Planning Algorithm for UAV Borne Air-to-Surface Missile
Authors: Yang Kai , Xu Chen , Xu Yan
Published: January 2021

This paper firstly introduces the development of domestic UAV borne air-to-ground missile guidance control systems and summarizes the current and ongoing research on the trajectory design of airborne missiles for unmanned aerial vehicles. Secondly, it introduces the traditional single-mode guided unmanned aerial vehicle air-to-ground missile trajectory design schemes and the new trajectory planning schemes for multi-mode compound guidance unmanned aerial vehicle borne air-to-ground missile. Finally, through mathematical simulation, it shows the characteristics of different trajectory schemes in terms of range, relative launch altitude and off-boresight capability.
Effect of graphene nano-platelet reinforcement on the mechanical properties of pressureless-sintered boron carbide
Authors: Li Z P , Gao X J , Lin G Q , Sun S L , Li K , Yang S Y , Fang S J , Zhang W , Zhang T , Wu Y C
Published: January 2021

Boron carbide (B4C) doped with graphene nano-platelet (GNP) as reinforcement has been prepared by pressureless sintering. Effect of GNP addition on mechanical properties of the composite, such as fracture toughness, hardness, flexural strength was investigated. Phase evolution and microstructure was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results demonstrated that addition of GNP improved the fracture toughness (KIC) of B4C with the decrease of hardness, flexural strength. The fracture toughness (KIC) can reach 4.45 MPam1/2 with 1wt% addition of GNP, which was 49.3% higher than that of the composite without graphene platelets. It was found that the toughening mechanism can be contributed to pulling-out of graphene platelets, crack deflection, bridging and branching.
Design of electronic control system for Z-pin four-axis numerical control implant reinforcement equipment
Authors: Chen H H , Meng F J , Zhang D S , Miao L Q , Guo H B , Du J , Sang M
Published: January 2021

Using the high-stability controller Delta AS324MT and the advanced high-precision servo system through the CANOPEN bus communication mode, the z-pin implantation is controlled with high precision and high efficiency, and the second encoder is applied to the qualifying mode to completely implement the closed-loop control of the qualifying length. Solve the technical problems such as the inaccuracy of the length and position, control the position precision and the precision of the implantation through the four-axis numerical control implantation method, and achieve the action control of the cutting by the joint pneumatic loop control. The actual test results show that this method improves the accuracy and efficiency of z-pin implantation, greatly saves the labor cost, and reduces the harm of manual implantation to the human body.
Study on Impact Resistance of Composite Reinforced Thin-Walled Tubes
Authors: Kuai Tengfei , Zhang Xianfeng , Chen Hejuan , Wang Jipeng , Ren Jie
Published: January 2021

In order to further improve the impact resistance of composite multi-cell thin-walled structures under axial loading, a new type of composite multi-cell sandwich tubular structure is proposed. Based on the MAT54 material model and the Chang-Chang failure criterion, a composite laminated shell modeling method was developed to simulate the failure behavior of the material under axial compression load and verified by quasi-static compression tests. The effectiveness of the simulation model is verified by comparing the parameters of peak load and specific energy absorption. The impact-resistance sensitivity of cell number and sandwich structure in composite multicellular structure was studied by this model. The results show that number of cells have a significant effect on the specific energy absorption of the composite multi-cell structure.
Near-explosion failure of elman neural network based on bootstrap
Authors: Zhao X , Liu S F , Ji Y X , Luo X B
Published: January 2021

In this paper, for the fuze of a certain type of fuze, there is a phenomenon that the fuze function of the fuze is invalid. The method of using the Bootstrap method to resample the experimental data, increase the sample size, and obtain the regular data, and use the back propagation neural network to establish the fuze near-failure learning model, and obtain a more accurate model by training the model. Test data is brought into the model and its accuracy is verified to ensure the accuracy of the model. It provides model support for the analysis of the weak condition of the fuze near-explosion function failure, and provides reference for the analysis of other fuzes.
The study on plastic flow behavior and constitutive model of h96 brass alloy under compression
Authors: Guo J H , Sun Y J , Liu Q , Ma Sh , Yang J W , Zhang X D
Published: January 2021

The plastic behavior of H96 brass alloy under a wide range of temperatures ranging from 20°C to 600°C and strain rates ranging from 0.01 s−1 to 6300 s−1 was studied by Gleeble-3500 simulator and split Hopkinson bar test. The results show that the flow stress increases with the strain and strain rate, while decreases with the temperature. The flow behavior is modeled by Johnson-Cook model and the parameters were obtained by regressions. The effect of strain rate and temperature on the flow stress was studied by modified JC model.
Fuzzy pid control of electromechanical actuator system
Authors: Li Cuicui , Yi Wenjun , Yin Hongqiao , Guan Jun
Published: January 2021

In order to meet the needs of modern high-performance aircraft, the fuzzy PID control strategy was used to design the electromechanical actuator control system. This control strategy combines the advantages of fuzzy control and PID control, and has better adaptability to time-varying complex systems. The electromechanical actuator control system adopted the three-loop structure, and current loop, speed loop and position loop were built on the platform of MATLAB / Simulink. Considering that the discrete universe fuzzy PID control algorithm has good real-time performance with small online computation, the fuzzy PID controller in discrete universe was designed in the position loop and the system was simulated. The simulation results show that the dynamic and steady performance of discrete universe fuzzy PID control is better than that of traditional PID control, and it is more suitable for electromechanical actuator system.
Matching research of the ammunition-feed system with the MBT overall performance
Authors: Wang Dongji , Yu Shasha
Published: January 2021

The ammunition-feed system (AFS) is one of the key systems of a MBT (Main Battle Tank), having general and much impact on the MBT overall performance. To assess the impact and technical level of AFS projects synthetically, accurately and quantifiably in order to choose the project according with overall requirements from many projects as well as possible, it is necessary to establish an index assessment system. In this paper, based on the analysis of the relationship between performance of the AFS and the MBT overall, an AFS’s matchability with the MBT overall concept is proposed, as well as the related assessment index. Taking the typical AFS in MBTs all over the world as the examples, AFS’s matchability with MBT overall is analyzed and evaluated through AHP (Analytic Hierarchy Process), which is a common system engineering methodology, and the application process of the index assessment system is displayed. In the end, the problems needing attention and advice during operation are given.
Tests of igniter’s charge position influence on ballistic parameters of artillery rounds
Authors: Plachá A , Hipnarowicz K
Published: January 2021

This paper presents a shooting test’s results of igniter’s charge position influence on ballistic parameters of artillery rounds. By igniter charge is meant black powder charge used to transmit ignition from igniter to propellant charge. For shooting tests 100 mm artillery rounds for BS-3 cannon, with NDT-3 18/1 and 15/7 propellants in different configurations of igniter’s charge position were prepared: igniter charge on the bottom of the metal case (A), igniter charge in the perforated metal tube, centrally located along the propellant charge (B), igniter charge in the end of lengthening metal tube, centrally located along the propellant charge, near to the bottom of the projectile (C). Moreover there were few configurations between igniter’s charge position and propellant charges: igniter charge in position A with NDT-3 18/1 propellant charge (1A), igniter charge in position B with NDT-3 18/1 charge (1B), igniter charge in position C with NDT-3 18/1 (1C), igniter charge in position A with 15/7 charge (2A) and igniter charge in position B with 15/7 charge (2B). During each shot the muzzle velocity of the projectile and the pressure of the propellant gases were measured. Obtained results were compared with each other and the conclusions were formed.
Experimental study on the breaking of A-IX-2 explosive by submerged cavitation water jet
Authors: Zhang Y X , Lian P , Kang C , Chen S
Published: January 2021

It was investigated to break A-IX-2 explosive using the submerged cavitation water jet for emptying scrapped ammunitions charged A-IX-2 explosives. The Split Hopkinson pressure bar (SHPB) tests were firstly accomplished for A-IX-2 explosive to obtain its stress-strain mechanical properties. The breaking effect and its mechanism of the submerged cavitation water jet were investigated. The broken A-IX-2 explosives were tested by scanning electron microscope (SEM) to analyze the mesoscopic mode of cavitation water jet breaking A-IX-2 explosive. Finally, the internal temperatures of A-IX-2 explosive during the whole impact process were detected. The results showed that A-IX-2 explosive exhibits strain rate effect. The submerged cavitation water jet is available to use to empty ammunition charged A-IX-2 explosive and the maximum particle size is no more than 3cm. The fragmentation of the explosive by the submerged cavitation water jets is mainly caused by the combined action of micro-jets and shock waves generated by the collapse of cavitation bubbles. The mesoscopic mode is mainly the separation of crystals from binder and aluminum powder. The temperature change of A-IX-2 explosive in the whole process is about 20 °C.
Characteristics and experimental study of radar scattering foil
Authors: Xu W D , Yang J T , Yang X , Zhang Y , Zhou L
Published: January 2021

Aiming at the current situation that Doppler radar can use the echo frequency difference to avoid the interference of chaff and chaff clouds, by studying the average radar scattering cross section, bandwidth characteristics, horizontal drift speed, polarization characteristics of the foil. The performance of the Paller effect, etc., examined the foil’s ability to counter Doppler radar. The static test is used to test the performance of the foil. Experimental research shows that the composite foils of multiple sizes can increase the reflection loss of the composite foil and improve the interference efficiency. Uses round foil as the base material, and foil with mixed side length of 10mm can enhance the loss performance under various polarization conditions.
Analysis of the operational characteristics of the US Aircraft Carrier Battle Group
Authors: Shan Yongzhi , Huang Degang
Published: January 2021

According to the operational requirements of attacking the US Aircraft Carrier Battle Group, its defense capabilities are analyzed in this paper. Furtherly, the disadvantages of the defense capabilities are studied, and the effective means of defensive counterattack against the US Aircraft Carrier Battle Group are raised, which can be utilized to guide the operational applications of airborne weapons.
Systematic approach of guidance information reconstruction of laser strapdown guidance air-to-ground missile
Authors: Wang Dong , Chen Yun
Published: January 2021

The decoupling algorithm of laser strapdown guidance which can effectively suppress the disturbance rejection rate problem and a method of extracting line of sight angle rate are studied. Firstly, the decoupling mathematical model of strapdown seeker is established, the cause of the disturbance rejection rate problem of strapdown guidance is analyzed, and the time synchronization algorithm is designed to reduce the coupling of the attitude motion of the missile to the guidance information. Secondly, an extraction algorithm of line of sight angle rate is established, an extraction algorithm of filter parameters changing with the remaining flight time is designed to suppress the attitude oscillation of the initial phase of terminal guidance and improve the tracking speed of the last phase, and the extracted line of sight angle rate is compared with the output characteristics of the platform seeker. Finally, the effectiveness of the proposed line of sight angle rate extraction algorithm is verified by six degrees of freedom trajectory simulation, and the influence of disturbance rejection rate parasitic loop on strapdown terminal guidance accuracy is analyzed by simulation.
Identification of clandestine groundwater pollution source locations and their release flux history
Authors: Chakraborty A , Prakash O
Published: January 2021

Large numbers of untreated toxic wastes are often buried underground, as a method of disposal. Such methods of clandestine disposal have led to widespread pollution of groundwater resources. These methods of wastes disposal are often adopted to avoid the cost incurred in proper treatment of the waste and untraceability of such clandestine disposals. However, the effect of such disposals manifests in form of groundwater pollution, which if left unchecked would potentially pollute the entire aquifer. Such polluted aquifers need to be reclaimed by implementing proper remediation techniques. However, the effectiveness of any remediation technique would depend on the precise knowledge of the unknown pollutant source/s characteristics, in terms of their Numbers, their Locations and their Release Flux history referred to as NLRF. This study presents a noble technique for simultaneously estimating the unknown number of clandestine pollutant sources, their locations along with their release flux history. Simulated Annealing (SA) is used in Linked Simulation Optimization (LSO) based framework. In this developed methodology, the number of sources and their respective locations and release flux histories are treated as unknown decision variables, and are estimated simultaneously along with the source release flux history.
Analysis on the characteristics of eye movement and the evaluation of psychological perception for forest waterscape space
Authors: Gao Y , Sun X M , Zhang T , Zhan H
Published: January 2021

For landscape architects, how to provide a highly quality forest landscape for visitors has always been an important topic. This study based on the results of previous field observation, combined with eye tracking technology and psychological perception questionnaire, and used the Wilcoxon rank sum test, T test and Spearman’s rho correlation analysis in SPSS 23.0 to statistically analyze the data. The main purpose is to clarify the relationship between visual behavior characteristics and psychological perception evaluation of the forest waterscape space where tourists have more behavioral evaluations during forest walk. Main results are as follows: 1. There are differences eye movement behaviors of different types of forest waterscape space, especially in the visual span; 2. There are significant differences visitor’s psychological evaluation of different types of forest waterscape in five indices, which in whether the landscape content is changing, whether the color is rich, whether the color is bright, whether the space is open and whether you can see the distant landscape; 3. There is a correlation between human eye movement behavior and psychological perception evaluation in different types of forest waterscape spaces. The scenes with a large number of fixations also have higher satisfaction, and fixations count have positively correlated with the spatial perception evaluation results, which including plant diversity, landscape richness, permeability and the layering. That is to say, richness of landscape elements and color, permeability of the space and the regularity of the forest waterscape space affect the participants’ eye movement observation mode. Through the above analysis, we suggest that in the planning and design of forest waterscape space should be considerate the characteristics of different landscape elements, meanwhile we should pay attention to the interspersion of appropriate heterogeneous landscape space.
Precipitation distribution and forecasting in hurricane ‘Hermine’
Authors: He J Y , Zhu X G
Published: January 2021

Retrievals and forecasting of precipitation based on FY-3C microwave humidity and temperature sounder (MWHTS) are carried out to validate the possibility of microwave sounder in meteorological applications. Different from current research, a novel idea combining radiative transfer theory and historical statistical method is presented. Hurricane Hermine (the first hurricane to make landfall along the apalachee bay coast Since 1966) as a study case is chose to analyse the precipitation distribution and give forecasting results in 72 hours.
Study on the impact of tourism quality perception on tourists’ environmentally responsible behaviour in rural tourism areas
Authors: Yin L J , Zhang N , Chang Z Y
Published: January 2021

Most of existing research on tourists’ environmentally responsible behaviour (ERB) focused on natural tourism and eco-tourism, but there is little research result on rural tourism. This paper constructs a structural equation model with satisfaction as a mediating variable to study the impact mechanism of tourism quality perception (TQP) on tourists’ ERB in rural tourism areas. Through exploratory factor analysis, TQP is divided into three dimensions: resource quality perception, service quality perception, image quality perception; ERB is divided into two dimensions: compliance ERB and active ERB. The case study results in the Shitangrenjia rural tourism area of China show that TQP indirectly affects ERB with satisfaction as the mediating variable; the impact of TQP on the active ERB is significantly greater than that of compliance ERB. In addition, there are significant differences among the different dimensions of TQP on ERB. This research confirms that the quality of rural tourism area has an important implication on tourists’ ERB, which could provide theoretical basis and decision support for the improvement of tourism quality and environmental protection of rural tourism areas.
Research on key fundamentals and technical systems of Sponge City development in China
Authors: Yang Z , Li J Q , Che W , Wang W L , Zhao Y , Zhang H Z
Published: January 2021

The Chinese government has promoted Sponge City construction in the last five years. The premise for a “Sponge City” was based on the problem of accumulation and rapid discharge of various stormwater and water-environment issues during the urbanization process in China. With reference to the expansion of stormwater management in other developed countries, this study summarizes related research results in China. Unlike other stormwater management systems put forward by other countries, such as low impact development, water sensitive urban design, etc., this study investigates stormwater issues at the current developmental stage in China and comprehensively considers the integrated objectives, including water ecology, water security, water resources, water environment, and water culture. Aimed at transforming the traditional extensive urbanization model, it builds on the existing integrated system at the core of stormwater management, which connects with the sewage and / or water supply, and other related systems. This study describes and summarizes the Sponge City’s key fundamentals, targets, technical systems, and extensional relations to guide the further construction of Sponge City and provide important references for other countries.
Optimization of surge tank structures in hydropower station based on VOF method
Authors: Yang Z Y , Cheng Y G , Liu K , Wang Q , Yang F
Published: January 2021

During transient processes of hydropower stations, large surging waves under load rejection condition and air-trapped vertical vortices under start-up condition in surge tanks are the critical factors that influence the safety of hydropower stations. In this study, model tests and volume of fluid (VOF) model based three-dimensional (3D) simulations were conducted to check the rationality of surge tank structures in transient processes, and after intensive analysis, an optimized scheme was proposed. The results show that the original scheme leads to the violent water level fluctuations in steady operation and load rejection conditions, and some air-trapped vertical vortices occur during start-up process. The air-trapped vertical vortices can provide bubbles into the penstock, which is not permitted. With the impedance orifice and bottom plate shapes changed, the optimized scheme gives limited water level fluctuations during both load rejection and start-up conditions, and eliminates the step water falling and air-trapped vortex swirling phenomena effectively, meeting the requirements of design, construction and operation.
Analysis on the thrust bearing lubrication in pumped storage unit based on fluid-solid-thermal interactions
Authors: Cao J W , Zhai L M , Guo B , Lei H M , Ahn S H , Wang Z W
Published: January 2021

The bidirectional thrust bearings are used to balance the thrust load of the entire shaft system which play an important role in the pumped storage units. The lubrication is usually analyzed by simultaneously solving the Reynolds equation, energy equation, film thickness equation of the film and the heat conduction equation, elastic equilibrium equation of the pad. However, in this method the assumptions for the inlet temperature of the film and the wall heat coefficients on the pad greatly affect the numerical accuracy. This study used fluid-solid-thermal interaction method, built three dimensional (3D) FEM model for the pad and collar and the 3D CFD model for the oil film, and then analyzed the influence of the thrust loads and the Babbitt layer on the bearing performance. The results show that increasing the thrust load will rapidly decrease the minimum film thickness, increase the maximum pressure and maximum temperature on the pad. Increasing the thickness of the Babbitt layer on the pad sliding surface will increase the minimum thickness of the film, decrease the maximum temperature on the pad which improve the bearing lubrication.
Analysis of Characteristics of Volatile Organic Compounds Pollution in Atmosphere in Kuitun City and Countermeasures
Authors: Wang Linna , Yang Rongjiang , Men Chunyan , Gao Li
Published: January 2021

The "Kui-Du-Wu" area of Kuitun City is one of the largest petrochemical bases and important economic core areas in Xinjiang. According to the online monitoring data of total volatile organic compounds (VOCs) at Kuitun site, 102 species can be detected in the urban atmospheric environment volatile organic compounds, through the analysis of the sources of the top ten compounds with average concentration values throughout the year, their main sources are chemical production, oil volatilization, fuel combustion, and motor vehicle exhaust. The prevention and control countermeasures are to strengthen source control, implement pollution source compliance management, improve the city's comprehensive management level, and establish and improve a joint prevention and control system.
Application status and prospects of biological deodorization in China
Authors: Yuan Shuai , Liu He , Liu Miao
Published: January 2021

With the development of urbanization, industry, agriculture and aquaculture, malodorous pollution has become increasingly serious. Odour pollutants can be produced by non-biological or biological pathways, which not only have a great negative impact on the regional ecological environment, but also cause great harm to the health of local people and animals. Compared with physical method, chemical method and adsorption method, biological deodorization method has the characteristics of high odour removal rate, environmental friendliness and low cost. Biological method is gradually becoming the preferred technique for odour removal in some odour producing areas. In this paper, the mechanism, the patent application status and the application prospect of biological deodorization are summarized and analysed, so that we can have a deeper understanding of biological deodorization.
The Impact of Polysaccharides and Flavonoids in Black Fungus on Resistance to Oxidative Stress and X-ray Environmental Radiation
Authors: Guo Li , Ma Xue , Li Yang , Wang Peng
Published: January 2021

The antioxidant capacity and developmental inhibition to X-ray radiation of polysaccharides and flavonoids in Black Fungus were studied by scavenging ability of free radicals and damage rate of X-ray radiation cells. The results showed that polysaccharide-flavonoid compound with mass ratio of 32.3 had a higher antioxidant effect, and antioxidant complex descended X-ray radiation cell damage rate to 10.06%. The polysaccharides and flavonoids of Black Fungus had effective protection to oxidation and X-ray environment radiation.