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A fast and accurate model for the creation of explosion fragments with improved fragment shape and dimensions

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Defence Technology（防务技术） 2022年第2期18卷 159-169页

作者： david Felix Ian Colwill Paul Harris School of Computing Engineering&MathematicsUniversity of BrightonBrightonUK Engineering and Design(Alumni) University of SussexBrightonUK

Explosion models based on Finite Element Analysis(FEA)can be used to simulate how a warhead *** their execution times are *** protection systems need to make very fast predictions,before a fast attacking weapon hits the *** execution times are also needed in real time simulations where the impact of many different computer models is being ***,FEA explosion models are not appropriate for these real-time *** research presented in this paper delivers a fast simulation model based on Mott’s equation that calculates the number and weight of fragments created by an *** addition,the size and shape of fragments,unavailable in Mott’s equation,are calculated using photographic evidence and a distribution of a fragment’s length to its *** model also identifies the origin of fragments on the warhead’s *** results are verified against experimental data and a fast execution time is achieved using uncomplicated simulation *** developed model then can be made available for real-time simulation and fast computation.

关键词： Distribution of fragments Fragment shape Real-time simulation Cylindrical explosion

Ricochet quantification using a multiple sensor approach

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Defence Technology（防务技术） 2021年第2期17卷 305-314页

作者： Michael Muster Amer Hameed david Wood Centre for Defence Engineering Cranfield UniversityDefence Academy of the United KingdomShrivenhamSN68LAUK

This study investigates the ricochet behaviour of three different small-arms projectile types using a novel ricochet measuring *** results can be used to estimate the danger potential of ricochets on shooting ranges.A ricochet is the change of direction and velocity of a projectile after impacting an oblique *** impact produces strong vibrations on a rigid *** this impact,flexural waves travel radially outwards from the point of *** waves are used to determine the properties of the impactor with accelerometers situated on the target *** the use of two measurement plates,one can produce a ricochet and detect the velocity at the same *** are suitable for accurate momentum measurements of single ***,depending upon strike velocity and the impact angle,a ricochet can separate in multiple fragments after being *** the operational safety perspective,these fragments need to be detected,as *** approach of a coupled sensor concept was chosen to solve this *** sensors were additionally used to visualise the heat which is produced after penetrating a rubber layer pasted in front of the steel target *** this approach one was able to detect the position of *** investigations showed that the measurement system performance is better with a multiple sensor design,which includes accelerometers for the velocity,impact strength and partly the position measurement,while the thermographic sensor was used for the position measurement and partly the momentum *** investigated ammunition showed plausible fragmentation behaviour,and the results can already be used to estimate the danger potential of different ammunition *** projectiles fragment to small particles already after being deflected under a small ***,Full Metal Jacket projectiles with or without a steel core do not fragment under angles which are less than 5.The objective of the pa

关键词： Ricochet analysis Small-calibre ammunition Velocity measurement Thermography

Pico-washing:simultaneous liquid addition and removal for continuous-flow washing of microdroplets

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Microsystems & Nanoengineering 2022年第2期8卷 249-261页

作者： Michael J.Siedlik david Issadore Department of Bioengineering University of PennsylvaniaPhiladelphiaPA 19104United States

Droplet microfluidics is based on a toolbox of several established unit operations,including droplet generation,incubation,mixing,pico-injection,and *** the last two decades,the development of droplet microfluidic systems,which incorporate these multiple unit operations into a workflow,has demonstrated unique capabilities in fields ranging from single-cell transcriptomic analyses to materials *** unit operation that is sorely underdeveloped in droplet microfluidics is washing,exchange of the fluid in a droplet with a different ***,we demonstrate what we name the"pico-washer,"a unit operation capable of simultaneously adding fluid to and removing fluid from droplets in flow while requiring only a small footprint on a microfluidic *** describe the fabrication strategy,device architecture,and process parameters required for stable operation of this technology,which is capable of operating with kHz droplet ***,we provide an image processing workflow to characterize the washing process with microsecond and micrometer ***,we demonstrate the potential for integrated droplet workflows by arranging two of these unit operations in series with a droplet generator,describe a design rule for stable operation of the pico-washer when integrated into a system,and validate this design rule *** anticipate that this technology will contribute to continued development of the droplet microfluidics toolbox and the realization of novel droplet-based,multistep biological and chemical assays.

关键词： operations simultaneous removing

Analysis of the effect of bore centerline on projectile exit conditions in small arms

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Defence Technology（防务技术） 2022年第12期18卷 2160-2169页

作者： david Leonhardt Mark Garnich Miljenko Lucic College of Engineering University of CanterburyPrivate Bag 4800Christchurch8140New Zealand Novacam Technologies Inc. 277 Lakeshore Road Suite#4Pointe-ClaireQuebecH9S 4L2Canada

Most finite element models of small arms focus on an idealized barrel,typically one with a perfectly straight bore *** five different experimentally measured bore centerlines,this investigation analyzes the effect centerline nonlinearity has on projectile exit *** includes the effect of rotating a centerline through several *** using Abaqus/Explicit,this dynamic analysis simulates a single firing cycle for each *** jump is calculated for each model as a measure of the effects of warped *** warped centerlines have a small effect on barrel dynamics.

关键词： Finite element analysis Small arms Barrel dynamics Bore centerline

Olfactory dysfunction as a common biomarker for neurodegenerative and neuropsychiatric disorders

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Neural Regeneration Research 2023年第5期18卷 1029-1030页

作者： david Slabik Olga Garaschuk Department of Psychiatry and Psychotherapy Tübingen Center for Mental HealthEberhard Karls University of TübingenTübingenGermany Institute of Physiology Department NeurophysiologyEberhard Karls University of TübingenTübingenGermany

The sense of smell supports the identification and the safety of food,warns of danger/predators,and plays a key role in mating(Croy and Hummel,2017;Kondo et al.,2020;Tzeng et al.,2021).Via connection to the limbic system,it supports behavioral adaption and emotions and can detect fear,tears,and happiness in the body odor of others(Croy and Hummel,2017;Tzeng et al.,2021).

关键词： Kondo tears al.

Forest visualization at multiple scales for management and planning

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Science China(Technological Sciences) 2006年第z1期49卷 27-34页

作者： david J.Mladenoff Department of Forest Ecology and Management

In this study forests were visualized at various scales by placing individual trees into a forest with realistic sizes and densities. Tree images were used from two sources: high quality field photos and images created using graphic design software. The terrain, species composition, and tree sizes and density from forest inventory were all represented in GIS data format. In addition, non-tree objects and features that are essential for close-to-reality visualization were combined with the tree images in a 3-D visualization software package. We further portrayed stand level effects by animating a simulated fly-through of a forest. To visualize temporal change, a case study of four different forest patches was animated. The advantages of this approach comparing to other visualization approaches are: (1) it represents the forests with realistic individual tree images; and (2) it maintains both visual and informational realism in a forest viewable from within-stand to landscape scales. Thus, this approach is realistic in two aspects. First, it is almost as realistic as a photograph, and secondly, its information content is actual forest composition, density, and height.

关键词： 3-D, visualization, forest, landscape, multiple scales.

Ferroptosis:copper-iron connection in cuprizone-induced demyelination

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Neural Regeneration Research 2022年第1期17卷 89-90页

作者： Priya Jhelum Samuel david Centre for Research in Neuroscience and Brain Program The Research Institute of the McGill University Health CentreMontrealQCCanada

Redox active metals such as iron,copper,zinc,and manganese play important roles in promoting a variety of biochemical reactions essential for cellular *** is made possible by the ability of these metals to accept and donate *** in the form of iron-sulfur clusters and heme plays a key role in adenosine triphosphate generation in mitochondria as well as numerous other enzymatic *** the other hand.

关键词： function. copper metals

The embryology of persistent cloaca and urogenital sinus malformations

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Asian Journal of Andrology 2020年第2期22卷 124-128页

作者： david F M Thomas University of Leeds LeedsWest Yorkshire LS29JTUK

Cloacal malformations are characterized by the confluence of the lower urinary tract,the female reproductive tract,and the rectum to create a common channel with a single opening on the *** presence of a cloaca is a normal phase of early human embryological *** the 4^th and 7^th weeks of gestation,the cloaca undergoes subdivision to form the hindgut and urogenital *** of this process results in the congenital anomaly termed persistent cloaca(PC).The term urorectal septum malformation sequence(URSMS)is also used to describe this *** classic description of this process which is still cited in many standard textbooks dates from the 19th ***,this has been increasingly called into question by the findings of studies using modern scientific *** sinus anomalies are defined by the confluence of the urethra and vagina to form a common channel of varying length with a single perineal *** this condition,the anorectal canal opens separately on the *** presence of a urogenital sinus represents a transient phase of the normal development of the lower genital tract in the female ***,the form of urogenital sinus most commonly encountered in the developed world is a feature of disordered sexual differentiation and does not arise simply from the persistence of the anatomical structure which is a feature of normal fetal development.

关键词： cloaca embryology urogenital sinus

Quantitative Stability of the Brunn-Minkowski Inequality for Sets of Equal Volume(Dedicated to Professor Haim Brezis on the occasion of his 70th birthday)

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Chinese Annals of Mathematics,Series B 2017年第2期38卷 393-412页

作者： Alessio FIGALLI david JERISON The University of Texas at Austin Mathematics Dept.RLM 8.1002515 Speedway Stop C1200AustinTX 78712-1202USA. Department of Mathematics Massachusetts Institute of Technology77 Massachusetts AveCambridgeMA 02139-4307 USA.

The authors prove a quantitative stability result for the Brunn-Minkowski inequality on sets of equal volume: If |A| = |B| > 0 and |A + B|^(1/n) =(2 + δ)|A|^(1/n) for some small δ, then, up to a translation, both A and B are close(in terms of δ) to a convex set *** this result was already proved by the authors in a previous paper, the present paper provides a more elementary proof that the authors believe has its own interest. Also,the result here provides a stronger estimate for the stability exponent than the previous result of the authors.

关键词： Quantitative stability, Brunn-Minkowski, Affine geometry, Convexgeometry, Additive combinatorics