bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on aero-engine blade surface detection based on three datum points integrating algorithm
Authors: Sun Bin , Zheng Gang , Zhang Xiongxing , Bai Lang
Published: July 2020

Aiming at the application of a 2D laser profile sensor in the detection of an aero-engine blade surface, a three-point alignment transformation algorithm based on a single-standard ball is proposed. In the algorithm, the standard ball is used to measure the coordinate conversion reference, and the three characteristic points, such as the center of the ball, the vertex, and the side extremum, are scanned by using a laser sensor once. When measuring the rotated blade, the laser sensor scans again, and the coordinate values of the three feature points in the new coordinate system are obtained through coordinate conversion technology. With these three pairs of feature points as the reference point for coordinate transformation and using a three-point alignment transformation and stitching algorithm, the 3D reconstruction of the blade profile measurement point cloud data can be accurately realized. The experimental results show that the 2D laser profile sensor can realize the on-line and fast detection of the aero-engine blade surfaces less then10 µm.
Environmental enrichment strategies for nursery piglets and efficacy for maintaining interest
Authors: de Oliveira G. F. , Caldara F. R. , Marcon A. V. , Martins R. A. , Crone C. , Garcia R. G. , Paz I. C. L. A. , Nieto V. M. O. S. , Odakura A. M. , Braz J. M.
Published: July 2020

Context
Animals in situations of stress and constant fear exhibit unwanted behaviours for production. Pigs that are afraid of humans tend to associate any management as stressful. The use of environment enrichment for pigs may help to alleviate anxiety and fear, and hence reduce unwanted behaviours during handling. However, provision of appropriate enrichment presents challenges such as the rapid loss of interest in objects by animals.

Aims
The present study evaluated the effects of different environmental enrichment strategies on the behaviour of pigs at the nursery stage, maintenance of animal interest in the enrichment objects, and their reflexes when faced with emotionally negative situations.

Methods
Piglets (n = 425) were assigned in a completely randomised design with five treatments and five replicates per treatment (17 animal per replicate). The treatments employed were: control, no enriching objects in the environment; WB, wooden box with popcorn and wood shavings; PT, objects made of plastic tubing; WB and PT concurrently; and WB or PT on alternate days. Behavioural observations were made over 10 days for 8 h each day, divided into four periods of 2 h. Piglets from enriched (n = 10) and non-enriched (n = 10) environments were subjected to three fear tests (human approach, novel object and novel arena).

Key results
No significant (P > 0.05) effect was found for the type of enrichment provided or strategy adopted (concurrent vs alternating) on the time piglets interacted with the enrichment objects. Animals kept in an environment with no stimulus had higher frequency (P < 0.05) of undesirable behaviours than those with enrichment, regardless of enrichment type or strategy adopted. Piglets reared without enrichment, when isolated in a new environment, had higher frequency of behaviours such as defecating, urinating and attempting escape, as well as more and longer vocalisation events (P < 0.05). Piglets reared in an enriched environment had higher frequency and duration of interaction with a new object, as well as shorter latency time for the first contact with the object (P < 0.05).

Conclusions
The use of enrichment objects in the rearing environment of piglets at the nursery stage reduced undesirable behaviours, suggesting reduced fear and anxiety, and may therefore improve their psychological wellbeing.

Implications
Use of enrichment objects during rearing may have implications for alleviation of chronic stress, which leads to constant release of cortisol, an immune suppressor hormone that reduces the health status of the batch and hence production indices.
The effect of preconditioning on production and antibiotic use in a South African beef feedlot
Authors: Hentzen A. H. R. , Thompson P. N. , Holm D. E.
Published: July 2020

Context There is pressure on production veterinarians to reduce the use of antibiotics in intensive beef production systems. Aims The present study investigated whether preconditioning – the process whereby weaned calves destined for the feedlot are prepared over a period of time – reduced antibiotic treatment events, and improved health and production of calves in a South African feedlot. Methods Preconditioned calves (n = 301) and control calves (n = 332) were sourced from the same origin on two occasions, and arrived at the feedlot on the same day. Bovine respiratory disease (BRD) was defined as the ‘pulling’ of clinically sick calves from feedlot pens, followed by the standard protocol for treatment of BRD (including antibiotic treatment). Outcome variables related to health were BRD overall incidence (pulling), BRD re-pulling and lung lesion scores. Production outcome variables measured were carcass weight, carcass average daily gain (ADG) and days on feed (DOF). Initial carcass weight was estimated from shrunk liveweight in order to estimate the effect of preconditioning on carcass gain, the most economically relevant outcome. Statistical analyses were done using multiple linear, logistic and Cox regression. Predictor variables were preconditioning vs control, gender, starting weight, DOF, pulling for BRD and carcass ADG. Key results A lower proportion of preconditioned calves were pulled and a lower proportion of pulled calves were re-pulled for BRD compared with control calves (8 vs 17% and 8 vs 16%, respectively, P < 0.01). A higher proportion of preconditioned calves compared with control calves were market ready at 90 DOF (89 vs 67%, P < 0.01). In the multivariable models preconditioning was associated with a 200 g/d increase in carcass growth rate (P < 0.01) and with a 17.7 kg increase in overall carcass gain (P < 0.01) after adjusting for gender and DOF. Conclusions Preconditioning reduced the incidence and severity of BRD and feedlot standing time and improved production of calves in South African feedlots. Implications Preconditioning has the potential to add value to the beef feedlot by reducing the formation of antimicrobial resistance while improving the profitability of the feedlot.
Corrigendum to: Impact of crop load on nitrogen uptake and reserve mobilisation in Vitis vinifera
Authors: Verdenal Thibaut , Spangenberg Jorge E. , Zufferey Vivian , Dienes-Nagy Ágnes , Viret Olivier , van Leeuwen Cornelis , Spring Jean-Laurent
Published: July 2020

Nitrogen deficit affects both crop production and composition, particularly in crops requiring an optimal fruit N content for aroma development. The adaptation of cultural practices to improve N use efficiency (NUE) (i.e. N uptake, assimilation and partitioning) is a priority for the sustainable production of high-quality crops. A trial was set on potted grapevines (Vitis vinifera L. cv. Chasselas) to investigate the potential of crop limitation (via bunch thinning) to control plant NUE and ultimately fruit N composition at harvest. A large crop load gradient was imposed by bunch thinning (0.5–2.5 kg m–2) and N traceability in the plant was realised with an isotope-labelling method (10 atom % 15N foliar urea). The results indicate that the mobilisation of root reserves plays a major role in the balance of fruit N content. Fertiliser N uptake and assimilation appeared to be strongly stimulated by high-yielding conditions. Fertilisation largely contributed to fulfilling the high fruit N demand while limiting the mobilisation of root reserves under high yield conditions. Plants were able to modulate root N reserve mobilisation and fertiliser N uptake in function of the crop load, thus maintaining a uniform N concentration in fruits. However, the fruit free amino N profile was modified, which potentially altered the fruit aromas. These findings highlight the great capacity of plants to adapt their N metabolism to constraints, crop thinning in this case. This confirms the possibility of monitoring NUE by adapting cultural practices.
Estimating soil organic carbon redistribution in three major river basins of China based on erosion processes
Authors: Yang Yan , Zhu Qiuan , Liu Jinxun , Li Mingxu , Yuan Minshu , Chen Huai , Peng Changhui , Yang Zhenan
Published: July 2020

Soil erosion by water affects soil organic carbon (SOC) migration and distribution, which are important processes for defining ecosystem carbon sources and sinks. Little has been done to quantify soil carbon erosion in the three major basins in China, the Yangtze River, Yellow River and Pearl River Basins, which contain the most eroded areas. This research attempts to quantify the lateral movement of SOC based on spatial and temporal patterns of water erosion rates derived from an empirical Unit Stream Power Erosion Deposition Model (USPED) model. The water erosion rates simulated by the USPED model agreed reasonably with observations (R2 = 0.43, P < 0.01). We showed that regional water erosion ranged within 23.3–50 Mg ha–1 year–1 during 1992–2013, inducing the lateral redistribution of SOC caused by erosion in the range of 0.027–0.049 Mg C ha–1 year–1, and that caused by deposition of 0.0079–0.015 Mg C ha–1 year–1, in the three basins. The total eroded SOC was 0.006, 0.002 and 0.001 Pg year–1 in the Yangtze River, Yellow River and Pearl River Basins respectively. The net eroded SOC in the three basins was ~0.0075 Pg C year–1. Overall, the annual average redistributed SOC rate caused by erosion was greater than that caused by deposition, and the SOC loss in the Yangtze River Basin was greatest among the three basins. Our study suggests that considering both processes of erosion and deposition – as well as effects of topography, rainfall, land use types and their interactions – on these processes are important to understand SOC redistribution caused by water erosion.
Contrasting effects of climate change on seasonal survival of a hibernating mammal
Authors: Cordes Line S. , Blumstein Daniel T. , Armitage Kenneth B. , CaraDonna Paul J. , Childs Dylan Z. , Gerber Brian D. , Martin Julien G. A. , Oli Madan K. , Ozgul Arpat
Published: July 2020

Significance

Climate change is altering the seasonal environmental conditions to which animals have adapted, but the outcome may differ between seasons for a particular species. Demographic responses therefore need disentangling on a seasonal basis to make accurate forecasts. Our study shows that climate change is causing seasonally divergent demographic responses in a hibernating mammal. Continued climate change will likely have a positive effect on summer survival but a negative effect on winter survival. This potentially has wide-ranging consequences across other species occupying temperate to more extreme arctic and alpine habitats, which are also where the most rapid changes in climate are observed.
Label-free optical detection of bioelectric potentials using electrochromic thin films
Authors: Alfonso Felix S. , Zhou Yuecheng , Liu Erica , McGuire Allister F. , Yang Yang , Kantarci Husniye , Li Dong , Copenhaver Eric , Zuchero J. Bradley , Müller Holger , Cui Bianxiao
Published: July 2020

Significance

Optical recording is highly desirable to detect bioelectric activities, as it can flexibly record a variety of user-selected locations. Here, we present ECORE, a label-free optical recording method that uses different principles than fluorescence-based voltage recording and offers independent advantages. ECORE utilizes voltage-dependent absorption of an electrochromic thin film and thus is not affected by photobleaching. ECORE offers spatial flexible and long-term optical recording without genetic or molecular perturbation.
Selective amplification of ipRGC signals accounts for interictal photophobia in migraine
Authors: McAdams Harrison , Kaiser Eric A. , Igdalova Aleksandra , Haggerty Edda B. , Cucchiara Brett , Brainard David H. , Aguirre Geoffrey K.
Published: July 2020

Significance

The melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) may contribute to photophobia in migraine. We measured visual discomfort and pupil responses to cone and melanopsin stimulation—the photoreceptor inputs to the ipRGCs—in people with and without migraine. We find that people with migraine do not differ from those without headaches in how cone and melanopsin signals are weighted and combined to produce visual discomfort. Instead, migraine is associated with amplification of ipRGC signals for discomfort. This effect of migraine upon ipRGC signals is limited to photophobia, as we did not find an enhancement of pupil responses or a change in other behaviors linked to ipRGC function. Our findings suggest a postretinal amplification of ipRGC signals for photophobia in migraine.
Alternative splicing of clathrin heavy chain contributes to the switch from coated pits to plaques
Authors: Moulay Gilles , Lainé Jeanne , Lemaître Mégane , Nakamori Masayuki , Nishino Ichizo , Caillol Ghislaine , Mamchaoui Kamel , Julien Laura , Dingli Florent , Loew Damarys , Bitoun Marc , Leterrier Christophe , Furling Denis , Vassilopoulos Stéphane
Published: July 2020

Clathrin function directly derives from its coat structure, and while endocytosis is mediated by clathrin-coated pits, large plaques contribute to cell adhesion. Here, we show that the alternative splicing of a single exon of the clathrin heavy chain gene (CLTC exon 31) helps determine the clathrin coat organization. Direct genetic control was demonstrated by forced CLTC exon 31 skipping in muscle cells that reverses the plasma membrane content from clathrin plaques to pits and by promoting exon inclusion that stimulated flat plaque assembly. Interestingly, mis-splicing of CLTC exon 31 found in the severe congenital form of myotonic dystrophy was associated with reduced plaques in patient myotubes. Moreover, forced exclusion of this exon in WT mice muscle induced structural disorganization and reduced force, highlighting the contribution of this splicing event for the maintenance of tissue homeostasis. This genetic control on clathrin assembly should influence the way we consider how plasticity in clathrin-coated structures is involved in muscle development and maintenance.
Targeting leukocidin-mediated immune evasion protects mice from Staphylococcus aureus bacteremia
Authors: Tam Kayan , Lacey Keenan A. , Devlin Joseph C. , Coffre Maryaline , Sommerfield Alexis , Chan Rita , O’Malley Aidan , Koralov Sergei B. , Loke P’ng , Torres Victor J.
Published: July 2020

Staphylococcus aureus is responsible for various diseases in humans, and recurrent infections are commonly observed. S. aureus produces an array of bicomponent pore-forming toxins that target and kill leukocytes, known collectively as the leukocidins. The contribution of these leukocidins to impair the development of anti–S. aureus adaptive immunity and facilitate reinfection is unclear. Using a murine model of recurrent bacteremia, we demonstrate that infection with a leukocidin mutant results in increased levels of anti–S. aureus antibodies compared with mice infected with the WT parental strain, indicating that leukocidins negatively impact the generation of anti–S. aureus antibodies in vivo. We hypothesized that neutralizing leukocidin-mediated immune subversion by vaccination may shift this host-pathogen interaction in favor of the host. Leukocidin-immunized mice produce potent leukocidin-neutralizing antibodies and robust Th1 and Th17 responses, which collectively protect against bloodstream infections. Altogether, these results demonstrate that blocking leukocidin-mediated immune evasion can promote host protection against S. aureus bloodstream infection.
Coordinate transformation and its uncertainty under consideration of a non-orthogonal coordinate base
Authors: Fern Florian , Füßl Roland , Eichfelder Gabriele , Manske Eberhard , Kühnel Michael
Published: July 2020

Nanopositioning and nanomeasuring machines are 3D coordinate measuring systems with nanometer precision at measurement volumes in the cubic centimeter range whose coordinate base is formed by an interferometer system with a common mirror corner. This mirror corner shows a typical deviation from the orthogonal coordinate base of up to 17 µrad with an uncertainty of 0.07 µrad. After a brief description of nanomeasuring and nanopositioning machines, a transformation model from the skewed coordinate system into the orthogonal coordinate system is determined. Starting from this complete transformation model, the result of model simplifications on the transformation behaviour is analysed and discussed. A GUM-based uncertainty calculation shows that the linearised coordinate transformation does not increase the error and the uncertainty significantly.
Unexpected crossovers in correlated random-diffusivity processes
Authors: Wang Wei , Seno Flavio , Sokolov Igor M , Chechkin Aleksei V , Metzler Ralf
Published: July 2020

The passive and active motion of micron-sized tracer particles in crowded liquids and inside living biological cells is ubiquitously characterised by ‘viscoelastic’ anomalous diffusion, in which the increments of the motion feature long-ranged negative and positive correlations. While viscoelastic anomalous diffusion is typically modelled by a Gaussian process with correlated increments, so-called fractional Gaussian noise, an increasing number of systems are reported, in which viscoelastic anomalous diffusion is paired with non-Gaussian displacement distributions. Following recent advances in Brownian yet non-Gaussian diffusion we here introduce and discuss several possible versions of random-diffusivity models with long-ranged correlations. While all these models show a crossover from non-Gaussian to Gaussian distributions beyond some correlation time, their mean squared displacements exhibit strikingly different behaviours: depending on the model crossovers from anomalous to normal diffusion are observed, as well as a priori unexpected dependencies of the effective diffusion coefficient on the correlation exponent. Our observations of the non-universality of random-diffusivity viscoelastic anomalous diffusion are important for the analysis of experiments and a better understanding of the physical origins of ‘viscoelastic yet non-Gaussian’ diffusion.
Test on the linear induction launcher with a new type of 3-phase helical coil
Authors: ShWang H , Chen Sh Zh , Li X , Liu J H
Published: July 2020

Different from the classical coaxial coils, a new type of asynchronous linear motor with helical 3-phase helical coil been brought forward in this paper. It has simple structures and produces peculiar travelling magnetic waves along the axis, which lead to the metal projectile is subjected invariable axial driving forces and rotary torques at the same time. It has a very useful property of this kind of winding, which is applied as a linear asynchronous launcher’s primary section. The high speed rotating projectile has stable flying attitude in moving direction because of the gyroscopic effect. The basic electromagnetic problems of the motor were discussed in this paper. An experimental model was build and tested to verify the principle results mentioned above at last.
Research on a multi-attribute comprehensive evaluation system for unmanned ground vehicles
Authors: Ding Yugang , Zhou Kedong , He Lei , Huang Xueying , Zhang Junbin , Wang Xikuo
Published: July 2020

To promote the development of unmanned ground vehicles, it is very necessary to establish a scientific and reasonable evaluation system for unmanned ground vehicles. This paper analyses the structure and operation of unmanned ground vehicles, and also proposes a multi-attribute comprehensive evaluation system for unmanned ground vehicles. Based on six aspects including environment perception, communication command, behavioural decision-making, human-computer interaction, weapon system and mobile platform, a new evaluation indicator system is established. In the quantitative process of qualitative indicators, Z-number theory is introduced to better describe the uncertainty degree of judgment and reasoning in human’s understanding of complex things. In order to make the indicator weights more scientific, the combined weighting model with analytic hierarchy process and information entropy is adopted for weight analysis, which not only takes into account the influence of evaluation experts on weights, but also reduces the subjective arbitrariness of weights. The least-squares grey relational analysis method is used to analyse the correlation between the comparison series and the reference series, and a comprehensive quantitative evaluation result of the unmanned ground vehicles is obtained. The evaluation examples of unmanned ground vehicles show that the proposed evaluation system can quantitatively evaluate the overall technical performance of unmanned ground vehicles. This evaluation system has high reference value for the evaluation of other complex weapons.
Influence of Taylor waves on standing windows of oblique detonation wave
Authors: Cui H , Gui M Y , Zhang L Y , Zhang H
Published: July 2020

An oblique detonation wave stabilized over a body has been studied due to the ongoing development of high-speed propulsion systems, such as oblique detonation wave engines and ram accelerators. Standing window of oblique detonation wave reflects the degree of standing difficulty. Firstly, Shock relations coupled with chemical equilibrium are solved to draw detonation polar diagrams between oblique detonation angle and wedge angle by iterative algorithm. In these diagrams, the wedge angle detaching from the wedge nose is referred as the maximum wedge angle θιηॉκ and forming CJ detonation in the direction normal to the oblique detonation wave is referred as the minimum wedge angle θख़τ. The region between the two wedge angles is regarded as the standing windows. G. Emanuel holds that Taylor waves follow the oblique detonation wave as the wedge angle is smaller than θख़τ. Based on reactive Euler equation, wedge-induced oblique detonation is simulated in this paper. For the case of the wedge angle below θख़τ, Taylor waves change post-detonation wave flow field to maintain standing oblique detonation wave. Therefore, the standing window becomes wider.
The new generation of air ammunition base on distribution and synergy technology
Authors: Guo J M , Shan Y Zh , Hu L F , Ma X D , Wang X G , Zhou Z H , Zhao H Y
Published: July 2020

In this study, the development of air ammunition was reviewed and the new technologies in weapons were summarized, the applications of distribution and synergy technology are proposed in air ammunition. Two representative types of operation were developed to use in battlefield, and the influences of weapons development in the future was analyzed.
Damage and fracture of gun barrel under wear-fatigue interaction
Authors: Wu B , Zheng J , Luo T F , Wang T , Zhou Y C , Huang X
Published: July 2020

Gun, projectile and propellant are three fundamental components of a launching system. Generally, a barrel has to be condemned after a number of rounds have been fired. During the total useful life of gun barrel, it bears severe damage induced from erosion by high pressure and high temperature propellant combustion gas, and wear due to high speed friction between projectile and gun bore. Meanwhile, the gun barrel undergoes a dynamic loading of gas pressure, mechanical stress and thermal stress when firing a round. Thousands of firing cycles lead to gun barrel fatigue. Interaction of wear, including erosion, and fatigue damages the gun barrel and eventually the gun will become inaccurate because of wearing away gun bore materials. However, a gun barrel will fracture in a sudden manner because of fatigue. It is found that microcracks form on the bore surface after only a few rounds have been fired, which lays the foundation for growth and propagation of cracks under fatigue loading. In this paper, laboratory hydraulic fatigue tests were carried out on a tube with pre-machined crack on its inner surface by using an MTS 809. Strain gauges were adhered to the outer surface of the tube to monitor strain during testing process. The hydraulic oil pressure was measured by a pressure sensor. The experimental results show that there are three stages of outer surface strain variation, namely stable increase, fast increase and abrupt increase, which corresponds to the history of crack evolution. Crack grew stably in the initial stage under cycle of loading and a major crack is gradually formed. When the major crack size reaches a certain value, the propagation velocity of crack is accelerated fast and the critical size is reached in a short time. Eventually the tube fractured suddenly. The experimental findings will help us to gain new insight into the physical mechanism of fatigue and fracture of gun barrel and provide a possible method to evaluate health of gun barrel in service.
Application of graded-index thin film in laser attack and defense equipment
Authors: Liu Yuanyuan , Chen Jianhua , Zhang Baoyu , Wang Guiyuan , Zhou Qibiao , Hu Huajun
Published: July 2020

Laser as a weapon used in contemporary warfare has been very common. As an important part of laser weapons, thin film plays an important role in laser attack and defense equipment. The manufacturing technology of graded-index thin film has always been a focus in the field of military science and technology and one of the key technologies to promote the development of laser weapons. This paper summarizes the present domestic situation of the graded-index thin film coating, and specifically introduces the application of graded-index thin film in laser equipment.
New insights into the reactionary zones excited-state programming by plasma-acoustic coupling mechanism for the next-generation small satellite solid propulsion systems
Authors: Lukin Alexander
Published: July 2020

Small satellites are changing the game for deep space missions because can work together in a fleet to take on more complex missions. Smart control by excited-state of the reactionary zones is one of the keys to access to the properties of the solid propellants reactionary zones. In particular, the self-organized wave patterns excitation occurs at excited-state of the reactionary zones. Use of the plasma-acoustic coupling mechanism is one of the advanced ways to access to the properties of the reactionary zones: the scale and localization of the induction and energy-releasing areas. On the base of detailed analysis we suggest the new concept for the reactionary zones programming by the plasma arc force field emitter with application of the self-organized wave patterns excitation phenomenon. The innovative aspect of this concept is the plasma-acoustic coupling mechanism that transforms the input electrical energy into the directed acoustic energy. Suggested concept for manipulating by self-organized wave patterns in the reactionary zones with using of the plasma arc force field emitters and new generation of the electrically activated solid propellants is opening the door for completely new ways for producing extremely small thrust impulses for the extra-precise attitude control of the small satellites.
A novel energetic composite with a special sandwich microstructure: RDX/expanded graphite intercalation composite
Authors: Ma X L , Chen Sh S , Chen K , Li L J , Zhao J J , Yang X B , Shang F Q , Lv X J , Shu Q H
Published: July 2020

In this paper, the RDX/expanded graphite (EG) intercalation composites were prepared by solvent/anti-solvent process to recrystallize RDX crystals into the holes, gaps and grooves of EG with controllable embedding ratio (maximum 87.0 wt%) and crystal size. RDX in the composites was in the most stableα-phase, which was benefit for its further application in the military industry. The stability and sensitivity of RDX were improved with higher melting and thermolysis temperature, activation enthalpy (ΔH
≠), critical temperature of thermal explosion (T
b) and lower mechanical sensitivity. The advanced half-coated parallel multi-sandwiches microstructure of RDX/EG intercalation composites possessed two effects: (i) high heat conduction and (ii) hot spots isolation of the carbon microstructure, which were the key to higher performance.
Fabrication and Characterization of Al-CuO nanocomposites prepared by Sol-Gel method
Authors: Wang Y T , Xu J B , Shen Y , Wang Ch G , Yang T L , Li F W , Zhang Z H , Chen J , Ye Y H , Shen R Q
Published: July 2020

Nanothermites are a class energetic material containing both fuel and oxidizer which undergo a very rapid redox reaction and release energy in a fast manner. In most formulations, aluminum(Al) was preferred fuel because of its abundance and high calorific value, and the oxidizer, such as Bi2O3, CuO, Fe2O3, MoO3, were generally used in the reactions. Compared with conventional EMS (energetic materials), Nanothermites demonstrate higher reaction rate and higher energy density due to reducing the diffusion distance between fuel and oxidizer.
Development of the analytic relations for the propellant grain geometrical characteristics required for a maximum pressure plateau feature
Authors: Rotariu A N , Bucur E , Cirmaci-Matei M V , Matache L C , Trana E
Published: July 2020

By using the fundamental interior ballistics relations, developed based on some simplification hypothesis, there was deduced a formula for the geometrical characteristics that allow the occurrence of a constant pressure plateau in a gun when a charge composed by a single type of undeterred propellant grain is used. The equation incorporates various factors as propellant ballistics properties, the gun/projectile/propellant gabaritical data and the targeted maximum pressure value. Nevertheless, the calculus done on a realistic set of data indicates the impossibility to reach a constant pressure plateau when a propellant characterised by a single set of geometrical characteristics over the entire web thickness is use.
Modelling and experiments of enclosure solid-propellant fires
Authors: Mense M , Pizzo Y , Lallemand C , Sardoy N , Porterie T , Pouschat P , Porterie B
Published: July 2020

In order to simulate an accidental propellant fire, blocks of aluminized solid rocket propellant, with mass in the range of 2-11 kg, were burned in a full-scale enclosure representative of an ammunition storage room onboard naval vessel. Wall heat flux and temperature, as well as gas pressure and temperature were measured to provide information regarding fire behaviour and thermal response of the structure. Burn characteristics of the propellant block, including shape and geometry, were deduced from visible and infrared images. The role of confinement, interior wall insulation or water spray on fire consequences was also investigated. Simulation results from a global model were compared to some experimental data. Agreement and discrepancies were identified.
Effects of binder on molding properties of HATO-based explosives
Authors: Yao L N , Han Zh X , Wang C L , Zhao Sh X , Dai Zh X
Published: July 2020

The safety performance of HATO explosives coated by Fluororubber and energetic thermoplastic elastomer ETPE were discussed, and it was analyzed that the influence of pressure and temperature on the moldability of HATO-based explosives with different binders. The results showed: the mechanical sensitivity of HATO explosives coated by binder were low, which improved the safety of HATO explosives to a certain extent; Pressure and temperature have a greater impact on the mold-ability of HATO-based mixed explosives containing Fluororubber or ETPE binder, and the mold-ability of HATO-based mixed explosives containing ETPE binder is better, which relative density can reach more than 98% at room temperature.
The analysis of the equivalent bare charge of aluminum cased charge exploding in confined space
Authors: Zhou Hu , Kong Xiangshao , Zheng Cheng , Wu Weiguo
Published: July 2020

The blast loadings from a cased charge, which include a cluster of fragments and shock waves, would cause severe damage to the structures, especially in the scenario of a confined space. In this paper, experiments of the dynamic response of steel plates subjected to the confined blast loading from a cased charge were performed, in which two set warhead models of aluminum cased TNT charge were employed. By using the explicit dynamic code AUTODYN and the Smoothed Particle Hydrodynamic (SPH) method, the rapture process of the aluminum shell was reproduced and the equivalent bare charge was determined by analyzing the results from numerical simulations. In addition, the dynamic response of steel plates subjected to confined blast loadings from cased charges were calculated numerically. Then, the method for calculating the equivalent bare charge that related to the deflection of blast loaded plates was proposed. In addition, this method was further used to determine the approximate mass of TNT charge that contributing to the blast loading of shock wave and subsequent quasi-static pressure in the confined space, in which the energy released by the burning of the detonation products and aluminum shell were taken into account. The present paper presented a reliable method to analyze the response of steel plates under confined blast loadings from a cased charge, which would be useful in the design of the protective structures.
Dynamic spherical cavity expansion analysis of concrete/rock based on Hoek-Brown criterion
Authors: Dong H , Wu H J , Li J Zh , Pi A G , Huang F L
Published: July 2020

Cavity expansion theory has been widely applied to predict the penetration depth of projectiles into geological materials, in which the yield criterion and the constitutive model are combined to describe the shear and compaction of the material, separately. For a precise description of the material behaviors in plastic for geological materials with varied compressive strength, in this present manuscript, the Hoek-Brown yield criterion and the Dilatant-Kinematic equation were introduced into the plastic region. A response region called elastic-cracking-dilatant-compaction region for concrete and rock was established. Then the effects of various parameters, including brittleness coefficient, material integrity coefficient and dilatant coefficient, on the relationship between cavity pressure and normal expansion velocity were discussed. Finally, a penetration depth formula of rigid projectiles into semi-infinite concrete and rock targets was established. It showed that, compared with the classical Forrestal model, the proposed model had a well-being as well as higher accuracy prediction of the penetration depth of concrete and rock materials with various strengths.
Exhausted jet caused the deformation of front metal seal covers in a multiple launch rocket system
Authors: Liu Z P , Zhao J X , Ma G J , Gao X F , Jiang L
Published: July 2020

During the launch tests of a Multiple Launch Rocket System (MLRS), the front metal seal covers on unlaunched tubes had plastic deformation and felled to the ground. More seriously, the rocket exhausted jet directly caused damage to some of the unlaunched rockets projectiles. As the rocket exhausted jet impinged on the cover, high temperature and high pressure jet caused plastic deformation of the covers. So the temperature and pressure of exhausted jet acting on the surface of the cover were measured. Then pressure data were used to estimate the strain of front cover on adjacent launch tube caused only by pressure. And temperature data were used for thermal stress analysis of the cover. Furthermore, the triaxial strain curves of the cover were obtained during a flight test in which a 252-mm diameter rocket projectile was launched from the MLRS. The results demonstrated that plastic deformation of the covers is mainly due to the thermal deformation caused by the high temperature, which provided guidance for optimal design of front seal covers. No plastic deformation was found in the modified covers during subsequent launch tests of the MLRS.
Optimization of the specific kinetic energy of the pre-grooved stun grenade fragments based on HyperMesh, LS-DYNA and Matlab
Authors: Liu Xing-yu , Ren-jun Zhan , Yong-li Li
Published: July 2020

Large-scale fragments formed by packaging shell of stun grenade are easy to cause irreversible damage to human body in close range. In order to reduce the specific kinetic energy of shell fragments as much as possible, the pre-grooving method is proposed to optimize the safety of packaging shell. According to the process of fragment forming, flying and impacting, the shell breaking model, fragment dispersion model and average specific kinetic energy calculation model are established respectively. The non-grooved shell and inner grooved shell are simulated by the joint simulation method of HyperMesh, LS-DYNA and Matlab. The fragment mass distribution, initial velocity and average specific kinetic energy are obtained and compared. The results show that under the same main charge parameters, the mass distribution of fragments is more concentrated and the large mass fragments are less in the inner grooved shell than in the non-grooved shell; the average initial velocity of fragments in the inner grooved shell is lower than that in the non-grooved shell; the attenuation of average specific kinetic energy in the inner grooved shell is faster than that in the non-grooved shell, which is safer than that in the non-grooved structure.
Study on shock initiation of the charge covered by metal plate with penetrated notch
Authors: Chen X W , Wang J X , Tang K , Wang H F , Li Y B
Published: July 2020

To analyze the coupling damage effect of high-speed fragments and near-field strong shock wave on the covered charge, a theoretical model of the shock initiation of the charge covered by metal plate with defects was established. The defect of the covered plate was simplified as a penetration notch, and the evolution characteristics of the shock wave in the notch were analyzed theoretically. The critical condition of the explosive detonation was determined by combining the explosive initiation criterion and the shock wave evolution characteristics. Take TNT covered by steel plate with a penetrated notch as an example, the nonlinear finite element program was used to simulate the shock initiation process of pressed charge, and the validity of the numerical simulation was verified by experimental results. The influence of the intensity of the shock wave, the thickness of the covered metal plate as well as the geometrical characteristics of the penetrated notch on the shock initiation of the pressed charge were analyzed by combining the theoretical model and numerical simulation results. The relationship of the notch size of the covered plate and the detonation distance was obtained by fitting, and the parameters n and K of the critical initiation criterion were obtained by least squares method. The theoretical calculation results and the numerical simulation results are agree with each other well and show that, the covered metal plate is beneficial for the protection of the charge. The existence of notch will weaken the protective performance of the covered plate, and the shape and size of the notch are also important factors that will affect the critical detonation distance of the charge. For the pressed TNT with and without 45# steel covered plate with the thickness 3 millimeters, the critical detonation distance of non-contact explosion was 13 millimeters and 81 millimeters, respectively. For the covered plate with a cylindrical notch, the critical detonation distance of the pressed TNT increases with increase of the diameter of the covered plate. For the covered plate has a frustum notch, the critical detonation distance of the pressed TNT decreases with increase of the slope in normal reflection.
Internal explosion load distribution and strain response of ellipsoidal end cover of explosion containment vessel
Authors: Hu Y H , Gu W B , Liu J Q , Han Y M , Wang Z
Published: July 2020

As a kind of limitation device of explosive products and shock wave, explosion containment vessel is widely used in military and civil fields. Due to its own structural characteristics, Mach wave convergence and collision will occur near the pole of the end cover of the cylindrical explosion containment vessel, resulting in a great pressure jump and seriously affecting the strain response characteristics of the end cover. In this paper, by means of experiment and numerical simulation, the distribution of flow field inside the end cover was explored, and it was found that the initial load of the end cover pole included the first incident wave of internal explosion, convergent re-incident wave of central section and the Mach wave convergence wave. By analyzing the strain spectrum, it is found that the different frequencies are excited by loads at different locations, so that the energy distribution under each frequency of strain is different, resulting in differences of strain. These results can provide reference for the design of explosion containment vessel.
Vibration-intensity prediction of underwater blasting based on grey relational analysis and dimension theory
Authors: Wang Z X , Gu W B , Zhao S T , Yu L F , P C  , Xu Jinglin
Published: July 2020

In addition to the distance from the blasting center and the charge amount, the influence of the water depth of the blasting zone and the difference in elevation between the measuring points are non-negligible for the vibration intensity of underwater blasting. Hence, the conventional Sadov’s formula is no longer fully applicable for the vibration-intensity prediction of underwater blasting. Combined with the vibration data of underwater blasting projects, a grey relational analysis of the influencing factors for blasting-vibration intensity has been conducted. The obtained order of the influence degree, from high to low, is the charge amount, elevation of the measuring point, water depth of the blasting zone, and the distance from blasting center. A formula for vibration-intensity prediction that comprehensively considers the influencing factors was derived from dimension theory; this formula is similar to Sadov’s formula. The comparison of the two prediction results showed that the average error of the formula considering the water depth of the blasting zone and the difference in elevation was below 10%. This showed a significant improvement in the prediction accuracy, compared with the Sadov’s formula, indicating that this derived formula is applicable for the vibration-intensity prediction of underwater blasting on land measuring points.
The Mechanism of Liquid Dispersing from a Cylinder Driven by Central Dynamic Shock Loading
Authors: Li L , Lu X X , Ren X B , Ren Y J , Zhao Sh T , Yan X F
Published: July 2020

A systematic investigation on the mechanism of dynamic liquid dispersing process via theoretical and experimental approach is presented. Based on the experimental results, dynamic analysis, one-dimensional characteristics analysis and some numerical simulation are carried out. The stretching and shearing actions, spall fracture mechanism and characters of cavitation layered are explored. Then the thermodynamic non-equilibrium process, metastable liquid dispersing, cavitation generation and some multiscale mechanisms are revealed.
Theoretical calculation for overpressure of air shock wave of explosion induced reaction of reactive material case
Authors: Du N , Zhang X F , Xiong W , Wang J P , Chen H H , Huang B Y
Published: July 2020

In order to study the power of the air shock wave produced by the reactive material driven by explosion, the reaction behavior of the reactive material driven by explosion was analyzed by AUTODYN@ software, and the reaction law of the reactive material was obtained. Considering the chemical energy released by the reactive material, the calculation model of shock wave initial parameters is improved. Combined with dimensional analysis, the theoretical calculation model for overpressure of air shock wave generated by the reactive material driven by explosion is studied. The results show that, under the driving of explosion, the casing made of the reactive material does not react completely. The velocity of air shock wave produced by the charge with reactive material casing is higher than that of the charge with inert material casing. The predicted value of the theoretical calculation model is in good agreement with the experimental results, and the established model can well describe the attenuation law of the air shock wave overpressure generated by the reactive material driven by the explosion.
The effect of shell material and load coefficient on the expansion of shell driven by detonation
Authors: Wang X Y , Wang Sh Sh , Lu X
Published: July 2020

Detonation driven metal expansion and fragmentation is a complex transient nonlinear dynamic problem. The research on the influence of the materials and load coefficients on expansion driven by detonation can provide a basis for fragment velocity prediction and warhead design. The numerical simulation of detonation driving was studied, including the TNT charge with five kinds of materials and six kinds of load coefficient β values shells. The characteristics in detail which the experiment was difficult to reflect were obtained, and the influence of material properties and β value of metal shells on the fragment velocities were revealed. With the increase of the density of the material, the dissipative energy of the shock wave in the casing decreases, and the contribution of the shock wave loading to the velocity of the fragment increases. Meanwhile, the increase of the shell wall thickness and the corresponding decrease of β value lead to the increase of the internal dissipation energy of the shock wave in the casings, the decrease of the energy for the shell expansion acceleration and the decrease of the contribution to the fragment velocity.
Analysis of dynamic back face deformation of a body armor impact by a rifle bullet using 3D-DIC
Authors: Wen Y K , Zheng H , Zhang J B , Yan W M , Cui G Y , Xu Ch
Published: July 2020

Body armor that defeats the threat can still cause severe trauma by striking the thorax with its back face deformation (BFD). In this study, the 3D digital image correlation (DIC) technology was adopted to capture the dynamic BFD of a ceramic/UHMWPE body armor impact by a rifle bullet. The shape and size of the BFD time histories, deformation velocity, acceleration and line slices profile on armor back face were obtained. The maximum BFD height can reach to 34.3 mm within about 1.2 ms, and then slowly decreases to the static deformation height of about 24mm for the impact velocity 675.4 m/s. The maximum deformation velocity and acceleration are 129.9 m/s and 1.29e6 m/s^2, respectively.
FBG testing on inside strain capturing of concrete blocks subjected to hard projectiles penetration
Authors: Gao D C , Yao W J , Ren Y , Wang R , Wu Q , Feng J
Published: July 2020

This study evaluates the terminal ballistics and strain behaviors of normal strength concrete blocks penetrated by hard ogival-nosed projectiles. Fiber Bragg Gratings (FBG) sensors are utilized herein to measure the radial strain responses inside concrete target during penetration process. With precise location, a novel method of FBG sensors embedment inside concrete block is proposed. The penetration tests are conducted with ballistic gun whereby the FBG sensor reflected signals are recorded. Consequently, Holmquist–Johnson–Cook (HJC) model is used to describe the concrete material dynamic behaviors. The LS-Dyna numerical penetration model is validated by Depth of Penetration (DOP) prediction. The numerical radial strain inside concrete target matches well with the experimental data by FGB testing.