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Modelling of internal ballistics of gun systems:A review

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Defence Technology（防务技术） 2024年第11期41卷 35-58页

作者： f.Ongaro C.Robbe A.Papy b.Stirbu A.Chabotier Royal Military Academy Avenue de la Renaissance 30Bruxelles 1000Belgium

A deep understanding of the internal ballistic process and the factors affecting it is of primary importance to efficiently design a gun system and ensure its safe management. One of the main goals of internal ballistics is to estimate the gas pressure into the combustion chamber and the projectile muzzle velocity in order to use the propellant to its higher efficiency while avoiding over-pressure phenomena. Dealing with the internal ballistic problem is a complex undertaking since it requires handling the interaction between different constituents during a transient time lapse with very steep rise of pressure and temperature. Several approaches have been proposed in the literature, based on different assumptions and techniques. Generally, depending on the used mathematical framework, they can be classified into two categories: computational fluid dynamics-based models and lumped-parameter ones. by focusing on gun systems, this paper offers a review of the main contributions in the field by mentioning their advantages and drawbacks. An insight into the limitations of the currently available modelling strategies is provided,as well as some considerations on the choice of one model over another. Lumped-parameter models, for example, are a good candidate for performing parametric analysis and optimisation processes of gun systems, given their minimum requirements of computer resources. Conversely, CfD-based models have a better capacity to address more sophisticated phenomena like pressure waves and turbulent flow effects. The performed review also reveals that too little attention has been given to small calibre guns since the majority of currently available models are conceived for medium and large calibre gun ***, aspects like wear phenomena, bore deformations or projectile-barrel interactions still need to be adequately addressed and our suggestion is to dedicate more effort on it.

关键词： Internal ballistics Numerical modelling Lumped-parameter model Computational fluid dynamics Gun systems

Inflow and outflow permeability tests in a very soft clay under low stresses

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 3270-3283页

作者： J.W.S.Vargas f.A.b.Danziger f.R.Lopes T.Lunne federal University of Rio de Janeiro Rio de JaneiroBrazil Norwegian Geotechnical Institute OsloNorway

In situ inflow and outflow permeability tests with the bAT probe at SarapuíII soft clay test site are presented.A description of the bAT permeability test is provided,discussing its advantages and shortcomings,especially in the case of very soft clays under low *** pressures were monitored during probe installation and were found to be slightly lower than piezocone u2 pore pressures,consistent with the position of the *** role of filter tip saturation was investigated after the usual saturation procedure provided an unsatisfactory pore pressure response during probe *** show that the vacuum saturation procedure provides adequate response during installation and increases the reliability of the coefficient of permeability determination in early *** inflow and outflow tests yielded similar results,indicating that careful execution of the test can lead to good test repeatability regardless of the loading *** sequences of alternated inflow and outflow tests have yielded similar results,indicating that soil reconsolidation and filter clogging were negligible in the tests *** are presented concerning the relationship between index parameters and the in situ coefficient of permeability for SarapuíII clay,which plot outside the range of existing databases.

关键词： Permeability test Soft clay bAT probe Inflow and outflow tests

Regression Equations for Predicting the Effect of Tine Width on Draught and Soil Translocation in Moderately fine Textured Soil

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Journal of Environmental Science and Engineering(b) 2012年第6期1卷 820-825页

作者： Seth Idowu Manuwa Olugboyega Cornelius Ademosun adebola Adesina Department of Agricultural Engineering School of Engineering and Engineering Technology The Federal University of TechnologyAkure 704 Nigeria

Experiments were conducted in an indoor soil bin filled with sandy clay loam soil. Tests were carried out with tillage tines to study the effect tool width on soil disturbance and draught. Depth of operation was held constant at 35 mm and then at 70 mm while speed was varied at three levels of 1.0, 3.6 and 9.0 km/h. The widths of the tines tested were 10, 20, 31, 40, 51, 88, 126, 163 and 200 mm. The cone penetration resistance of the soil varied from 400 to 600 kPa. Draught was measured with a load cell while soil disturbance was measured with a profile meter and meter rule. Draught increased at a decreasing rate with tine width. Quadratic models best fitted the data points with high R2 values. The increase in draught was affected by the forward speed since higher draught values were obtained at higher speed. Results show that the parameters of soil disturbance increased with increase in tine width, except height of ridge （hr）, which did not show any specific trend. The specific draught was highest （10.63 N/cm） with tine T20 while Tine T1 had the least specific draught of 5.2 N/cm.

关键词： Soil bin tillage tines draught soil disturbance parameters rake angle forward speed regression analysis

The Role of Information Security Development （ISD） in Effective Information Security Management （ISM） Implementation in the banks： A Nigerian Case

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Journal of Modern Accounting and Auditing 2014年第5期10卷 614-619页

作者： Dorcas adebola babatunde Mohamad Hisyam Selamat Ramat Titilayo Salman Universiti Utara Malaysia Kedah Malaysia SEGI University Selangor Malaysia University of Ilorin Ilorin Nigeria

This research discusses the role of information security development （ISD） using organizational factors such as information security plans, information security awareness, perceived quality training programs, information security policies and procedures, and organizational culture in effective information security management （ISM） implementation in the banks （a Nigerian case）. This paper explores the existing literature and a proposed framework that consists of ISD such as information security plans, information security awareness, perceived quality training programs, information security policies and procedures, and organizational culture in ISM implementation. ISD factors are found to be statistically significant, because it motivates an organization to implement effective ISM in the banks. Hence, it could be said that the role of ISD practices in an effective implementation of ISM among banks in Nigeria will be of great value.

关键词： information security management (ISM) information security plans perceived quality training programs organizational culture Nigeria

Molecular Characterization of Type II Transposable Elements in Cowpea [<i>Vigna unguiculata</i>(L.) Walp]

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American Journal of Plant Sciences 2015年第5期6卷 767-776页

作者： Olufisayo Kolade adebola Raji Iyiola fawole Ivan Ingelbrecht Crop Protection and Environmental biology Department University of Ibadan Ibadan Nigeria Present Address: biotechnology Laboratory Africa Rice Center Cotonou Benin Institute of Plant Sciences Iowa State University Ames IA USA bells University of Technology Ota Ogun State Nigeria Department of Plant biotechnology and bio-Informatics VIB-Ghent University Gent Belgium

Previous genetic studies in cowpea [Vigna unguiculata (L.) Walp] have shown that an active bipartite transposable element (TE) is responsible for a range of mutant phenotypes of its leaf, stem and flower. Since type II TEs have not been characterized at the molecular level in cowpea, this study was initiated to survey the presence of type II TEs in the cowpea genome. Type II TEs: Enhancer/Suppressor-mutator (En/Spm) and Miniature Inverted-repeat Transposable Elements (MITEs) were isolated and characterized. The sequence identity between the EnSpm TE clones was 46% at the nucleotide level (NL) and 30% at the amino acid level (AL) while that of MITEs was 71% at NL and 63% at AL. These cowpea En/Spm TEs were 80% homologous with En/Spm elements of other crops at NL and 46% at AL. The MITEs were 96% similar at NL and 18% homologous at AL. DNA gel blot analysis confirmed the presence of the En/Spm TEs in cowpea. RT-PCR (reverse transcriptase polymerase chain reaction) analysis showed that the VuEnSpm-3 and the MITE clone, VuPIf-1 were actively transcribed in wild type and mutant cowpea tissues. Overall, our data show that multiple, divergent lineages of En/Spm and MITEs are present in the cowpea genome, some of which are actively transcribed. Our findings also offer new molecular resource to further investigate the genetic determinants underlying previously described mutant cowpea phenotypes.

关键词： Cowpea En/Spm MITE Transposable Element Vigna unguiculata

RPLP0/TbP are the most stable reference genes for human dental pulp stem cells under osteogenic differentiation

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World Journal of Stem Cells 2024年第6期16卷 656-669页

作者： Daniel b ferreira Leticia M Gasparoni Cristiane f bronzeri Katiucia b S Paiva Laboratory of Extracellular Matrix biology and Cellular Interaction Department of AnatomyInstitute of Biomedical SciencesUniversity of São PauloSão Paulo 05508-000São PauloBrazil

bACKGROUND Validation of the reference gene(RG)stability during experimental analyses is essential for correct quantitative real-time polymerase chain reaction(RT-qPCR)data ***,in an unreliable way,several studies use genes involved in essential cellular functions[glyceraldehyde-3-phosphate dehydro-genase(GAPDH),18S rRNA,andβ-actin]without paying attention to whether they are suitable for such experimental conditions or the reason for choosing such ***,such studies use only one gene when Minimum Information for Publication of Quantitative Real-Time PCR Experiments guidelines recom-mend two or more *** impacts the credibility of these studies and causes dis-tortions in the gene expression *** tissue engineering,the accuracy of gene expression drives the best experimental or therapeutical *** cultivated DPSCs under two conditions:Undifferentiated and osteogenic dif-ferentiation,both for 35 *** evaluated the gene expression of 10 candidates for RGs[ribosomal protein,large,P0(RPLP0),TATA-binding protein(TbP),GAPDH,actin beta(ACTb),tubulin(TUb),aminolevulinic acid synthase 1(ALAS1),tyro-sine 3-monooxygenase/tryptophan 5-monooxygenase activation protein,zeta(YWHAZ),eukaryotic translational elongation factor 1 alpha(Ef1a),succinate dehydrogenase complex,subunit A,flavoprotein(SDHA),and beta-2-micro-globulin(b2M)]every 7 d(1,7,14,21,28,and 35 d)by *** data were analysed by the four main algorithms,ΔCt method,geNorm,Normfinder,and bestKeeper and ranked by the Reffinder *** subdivided the samples into eight *** All of the data sets from clonogenic and osteogenic samples were analysed using the Reffinder *** final ranking showed RPLP0/TbP as the two most stable RGs and TUb/b2M as the two least stable *** theΔCt method or Normfinder analysis showed TbP/RPLP0 as the two most stable ***,geNorm analysis showed RPLP0/Ef1αin the first *** algorithms’two least stab

关键词： Dental pulp stem cells Reference gene Housekeeping gene Endogenous gene Osteogenic differentiation Reffinder

A Geometric Distortion Solution Specifically for Historical Observations and its Implementation

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Research in Astronomy and Astrophysics 2024年第11期24卷 85-94页

作者： f.R.Lin Q.Y.Peng Z.J.Zheng b.f.Guo School of Software Jiangxi Normal UniversityNanchang 330022China Sino-french Joint Laboratory for Astrometry Dynamics and Space ScienceJinan UniversityGuangzhou 510632China Department of Computer Science Jinan UniversityGuangzhou 510632China Guangdong Ocean University Zhanjiang 524000China

Geometric distortion(GD)critically constrains the precision of *** well-established methods to correct GD requires calibration observations,which can only be obtained using a special dithering strategy during the observation ***,this special observation mode is not often used,especially for historical observations before those GD correction methods were *** a result,some telescopes have no GD calibration observations for a long period,making it impossible to accurately determine the GD *** limits the value of the telescope observations in certain astrometric scenarios,such as using historical observations of moving targets in the solar system to improve their *** investigated a method for handling GD that does not rely on the calibration *** this advantage,it can be used to solve the GD models of telescopes which were intractable in the *** method was implemented in Python and released on *** was then applied to solve GD in the observations taken with the 1 m and 2.4 m telescopes at Yunnan *** resulting GD models were compared with those obtained using well-established methods to demonstrate the ***,the method was applied in the reduction of observations for two targets,the moon of Jupiter(Himalia)and binary GSC 2038-0293,to show its *** GD correction,the astrometric results for both targets show ***,the mean residual between the observed and computed position(O-C)for binary GSC 2038-0293 decreased from 36 to 5 mas.

关键词： astrometry-methods data analysis-techniques image processing

Simulation of natural fragmentation of rings cut from warheads

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Defence Technology（防务技术） 2015年第4期11卷 319-329页

作者： John f.MOXNES Steinar b?RVE Land Systems Division Norwegian Defence Research Establishment

Natural fragmentation of warheads that detonates causes the casing of the warhead to split into various sized fragments through shear or radial fractures depending on the toughness,density,and grain size of the *** best known formula for the prediction of the size distribution is the Mott formulae,which is further examined by Grady and Kipp by investigating more carefully the statistical most random way of portioning a given area into a number of *** examine the fragmentation behavior of radially expanding steel rings cut from a 25 mm warhead by using an in house smooth particle hydrodynamic(SPH) simulation code called *** results were compared with numerical results applying varying particle size and stochastic fracture *** numerically obtained number of fragments was consistent with experimental *** expansion velocity of the rings increases the number of *** variation of the material parameters influences the fragment characteristics,especially for low expansion velocities.A least square regression fit to the cumulative number of fragments by applying a generalized Mott distribution shows that the shape parameter is around 4 for the rings,which is in contrast to the Mott distribution with a shape parameter of 1/*** initially polar distributed particles,we see signs of a bimodal cumulative fragment *** statistical variation in material parameters of the fracture model causes the velocity numerical solutions to become less sensitive to changes in resolution for Cartesian distributed particles.

关键词：弹头光滑粒子流体动力学自然环切膨胀速度模拟材料参数形状参数

Titanium Alloy Surface Modification by a Spatio-Temporal Atmospheric Pressure DbD Afterglow

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Plasma Science and Technology 2007年第6期9卷 670-673页

作者： E.PANOUSIS f.CLEMENT J.f.LOISEAU N.SPYROU b.HELD J.LARRIEU f.GUERTON Laboratory of Gas Electronics and Plasmas-Pau University 64000 PauFrance Electrotechnic Materials LaboratoryUniversity of Patras26500 Patras-RioGreece Laboratory of Gas Electronics and Plasmas-Pau University 64000 PauFrance Electrotechnic Materials Laboratory University of Patras26500 Patras-RioGreece Laboratoire Interdisciplinaire de Spectroscopie Electronique University of Namur5000 NamurBelgium

The experimental work reported here is devoted to the study of the modifications inflicted on the surface of titanium alloy specimens by an atmospheric pressure dielectric barrier discharge（DbD） reactor in both spatial and temporal afterglow conditions. A commercially available （AcXys Technologies） modified reactor system was used for the surface treatment of the TiA6V4 titanium alloy that is widely used in the aeronautical industry. Wettability surface characterisation and XPS analyses are performed to give a macroscopic and microscopic insight to the surface modifications. best operating conditions, at constant input energy, were obtained for a duty cycle equal to 10%.

关键词： DbD titanium alloy atmospheric pressure