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Measurement of bullet impact conditions using automated in-flight photography system

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Defence Technology（防务技术） 2017年第4期13卷 288-294页

作者： ryan Decker Marco Duca shawn Spickert-Fulton Armament Research Design and Engineering Center 94 Ramsey Avenue Picatinny Arsenal NJ 07806 USA

Knowledge of impact conditions is critical to evaluating the terminal impact performance of a *** a small caliber bullet,in-flight velocity has been precisely measured for decades using detection screens,but accurately quantifying the orientation of the bullet on a target has been more *** report introduces the Automated Small-Arms photogrammetry(ASAp)analysis method used to measure,model,and predict the orientation of a small caliber bullet before reaching an impact *** uses advanced hardware developed by Sydor Technologies to record a series of infrared digital *** images(four orthogonal pairs)are processed using computer vision algorithms to quantify the orientation of the projectile and re-project its precise position and orientation into a three-dimensional muzzle-fixed coordinate *** epicyclic motion model is fit to the measured data,and the epicyclic motion is extrapolated to the target *** results are fairly immediate and may be reviewed during ***-out demonstrations have shown that the impact-angle prediction capability is less than six hundredths of a degree for the 5.56 mm ball round ***:Yaw,Terminal ballistics,Exterior ballistics,Test&evaluation,Computer vision,Image processing,Angle of

关键词： Terminal ballistics Exterior ballistics Test & evaluation Computer vision Image processing Angle of attack

Experimental investigation of sediment transport in partially ice-covered channels

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International Journal of Sediment Research 2023年第5期38卷 769-779页

作者： Mina Rouzegar shawn p.Clark Department of Civil Engineering University of Manitoba

It is important to understand the effects of ice cover on sediment transport in cold climates, where subfreezing temperatures affect water bodies for a significant part of the year. The literature contains many studies on sediment transport in open channel flow, and several studies on sediment transport in completely ice-covered flow. There has been little or no research on sediment transport in partially icecovered channels. In the current study, laboratory experiments were done in a rectangular flume to quantify the impact of border ice presence on the sediment transport rate. The effects of ice cover extent and changing flow strengths on sediment transport distribution also were investigated, and the results were compared to those for fully ice-covered and open channel flow. The ice coverage ratios considered were 0(representing the open water condition), 0.25, 0.50, 0.67, and 1(representing fully ice-covered flow). The partial ice cover was found to impact the sediment transport distribution within the channel. The effect of ice coverage extent on sediment transport distribution was more significant at lower flow strengths and became negligible at higher flow strengths. The conventional equations for sediment transport in open channel flow and fully ice-covered flow that relate the dimensionless bedload transport rate to the flow strength were found to be applicable to estimate the total cross-section-averaged bedload transport for partially ice-covered flow when modified appropriately. Empirical coefficients for these equations were determined using the experimental data.

关键词： Sediment transport Bedload Ice-covered channel Border ice

Vasectomy reversal： a clinical update

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Asian Journal of Andrology 2016年第3期18卷 365-371,I0007页

作者： Abhishek p patel ryan p Smith Department of Urology University of Virginia Charlottesville VA 22908-0422 USA.

Vasectomy is a safe and effective method of contraception used by 42-60 million men worldwide. Approximately 3%-6% of men opt for a vasectomy reversal due to the death of a child or divorce and remarriage, change in financial situation, desire for more children within the same marriage, or to alleviate the dreaded postvasectomy pain syndrome. Unlike vasectomy, vasectomy reversal is a much more technically challenging procedure that is performed only by a minority of urologists and places a larger financial strain on the patient since it is usually not covered by insurance. Interest in this procedure has increased since the operating microscope became available in the 1970s, which consequently led to improved patency and pregnancy rates following the procedure. In this clinical update, we discuss patient evaluation, variables that may influence reversal success rates, factors to consider in choosing to perform vasovasostomy versus vasoepididymostomy, and the usefulness of vasectomy reversal to alleviate postvasectomy pain syndrome. We also review the use of robotics for vasectomy reversal and other novel techniques and instrumentation that have emerged in recent years to aid in the success of this surgery.

关键词： epididymovasostomy microsurgery postvasectomy orchialgia postvasectomy pain syndrome vas deferens vasectomy vasectomy reversal vasoepididymostomy vasovasostomy

Direct-to-indirect mapping for optimal low-thrust trajectories

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Astrodynamics 2024年第1期8卷 27-46页

作者： David Ottesen ryan p.Russell Department of Aerospace Engineering and Engineering Mechanics The University of Texas at AustinAustinTexas78712USA

Optimal,many-revolution spacecraft trajectories are challenging to solve.A connection is made for a class of models between optimal direct and indirect *** transfers that minimize thrust-acceleration-squared,primer vector theory maps direct,many-impulsive-maneuver trajectories to the indirect,continuous-thrust-acceleration *** mapping algorithm is independent of how the direct solution is obtained and requires only a solver for a boundary value problem and its partial derivatives.A Lambert solver is used for the two-body problem in this *** mapping is simple because the impulsive maneuvers and co-states share the same linear space around an optimal *** numerical results,the direct coast-impulse solutions are demonstrated to converge to the indirect continuous solutions as the number of impulses and segments *** two-body design space is explored with a set of three many-revolution,many-segment examples changing semimajor axis,eccentricity,and *** first two examples involve a small change to either semimajor axis or eccentricity,and the third example is a transfer to geosynchronous *** a single processor,the optimization runtime is seconds to minutes for revolution counts of 10 to 100,and on the order of one hour for examples with up to 500 *** of these thrust-acceleration-squared solutions are good candidates to start a homotopy to a higher-fidelity minimization problem with practical constraints.

关键词： direct optimization indirect optimization impulsive maneuvers Lambert's problem two-body dynamics primer vectortheory

A genome-wide association analysis implicates SOX6 as a candidate gene for wrist bone mass

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Science China(Life Sciences) 2010年第9期53卷 1065-1072页

作者： shawn LEVY Vanderbilt Microarray Shared Resource Vanderbilt University

Osteoporosis is a highly heritable common bone disease leading to fractures that severely impair the life quality of *** fractures caused by osteoporosis are largely due to the scarcity of wrist bone *** we report the results of a genome-wide association study (GWAS) of wrist bone mineral density (BMD).We examined ～500000 SNp markers in 1000 unrelated homogeneous Caucasian subjects and found a novel allelic association with wrist BMD at rs11023787 in the SOX6 (SRY (sex determining region Y)-box 6) gene (p=9.00×10-5).Subjects carrying the C allele of rs11023787 in SOX6 had significantly higher mean wrist BMD values than those with the T allele (0.485:0.462 g cm-2 for C allele vs.T allele carriers).For validation,we performed SOX6 association for BMD in an independent Chinese sample and found that SNp rs11023787 was significantly associated with wrist BMD in the Chinese sample (p=6.41×10-3).Meta-analyses of the GWAS scan and the replication studies yielded p-values of 5.20×10-6 for *** of this study,together with the functional relevance of SOX6 in cartilage formation,support the SOX6 gene as an important gene for BMD variation.

关键词： osteoporosis GWAS SOX6 SNps wrist BMD

Wildfire severity alters soil microbial exoenzyme production and fungal abundances in the southern Appalachian Mountains

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pedosphere 2024年第5期34卷 865-878页

作者： Megan L.SCHILL Richard BAIRD shawn p.BROWN Allison M.VEACH Department of Integrative Biology University of Texas at San AntonioSan Antonio TX 78249USA Biochemistry Molecular BiologyEntomology and Plant Pathology DepartmentMississippi State UniversityStarkville MS 39762USA Department of Biological Sciences The University of MemphisMemphis TN 38152USAAntonioand the University of Memphis。

Climate change has increased drought frequency and duration that are exacerbated by increased temperatures *** effect has,and will continue,to increase fire occurrence across many regions of North *** the southern Appalachian Mountains,wildfires with high burn severity occurred in 2016due to increased drought and human *** investigate the effects of burn severity on soil physicochemical properties,microbial extracellular enzyme production,and microbial abundances in a temperate region,surface soils(0-15 cm)were collected from two sites(the Great Smoky Mountains National park in Tennessee and the Nantahala National Forest in North Carolina,USA)spanning lightly,moderately,and severely burned areas,accompanied by adjacent unburned locations that act as *** soil samples were collected at three time points between 2017 and 2019(i.e.,0.5,1,and 2.5 years post-fire)among burn severity *** hydrolytic enzyme production varied over time,with severe burn plots having significantly lower enzyme production at 2.5years *** enzymes varied among burn severities and across time *** burn plots showed greater carbon-specific(β-glucosidase andβ-xylosidase)and phosphorus-specific(acid phosphatase)enzyme activities at 0.5 years post-fire,but this effect was *** 2.5 years post-fire,theβ-xylosidase and acid phosphatase activities were lower in severe or moderate burn plots relative to the *** contrast,the activity of nitrogen-specific enzyme leucyl aminopeptidase was the lowest in severe burn plots at 0.5 years post-fire,but was the lowest in light burn plots at 2.5 years *** fungi:bacteria ratio declined with burn severity,indicating that fungi are sensitive or less resilient to high burn severity during *** results suggest that wildfires alter trajectories for soil microbial structure and function within a 2.5-year timeframe,which potentially has long-term impacts on biogeochemical

关键词： burn severity extracellular enzyme fungi:bacteria ratio internal transcribed spacer microbial structure 16S rRNA

Demonstration of tantalum as a structural material for MEMS thermal actuators

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Microsystems & Nanoengineering 2021年第1期7卷 85-97页

作者： Longchang Ni ryan M.pocratsky Maarten p.de Boer CMU Mechanical Engineering Dept. 5000 Forbes Ave.PittsburghPA 15213USA present address:Fischione Instruments 9003 Corporate CirExportPA 15632USA

This work demonstrates the processing,modeling,and characterization of nanocrystalline refractory metal tantalum(Ta)as a new structural material for microelectromechanical system(MEMS)thermal actuators(TAs).Nanocrystalline Ta films have a coefficient of thermal expansion(CTE)and Young’s modulus comparable to bulk Ta but an approximately ten times greater yield *** mechanical properties and grain size remain stable after annealing at temperatures as high as 1000°*** has a high melting temperature(Tm=3017℃)and a low resistivity(ρ=20µΩcm).Compared to TAs made from the dominant MEMS material,polycrystalline silicon(polysilicon,Tm=1414℃,ρ=2000µΩcm),Ta TAs theoretically require less than half the power input for the same force and displacement,and their temperature change is half that of *** TAs operate at a voltage 16 times lower than that of other TAs,making them compatible with complementary metal oxide semiconductors(CMOS).We selectα-phase Ta and etch 2.5-μm-thick sputterdeposited films with a 1μm width while maintaining a vertical sidewall profile to ensure in-plane movement of TA *** is 25 times thicker than the thickest reactive-ion-etchedα-Ta reported in the technical *** stress sensitivities to sputter parameters and to hydrogen incorporation are investigated and ***,a V-shaped TA is fabricated and tested in *** conventional actuation by Joule heating and passive self-actuation are as predicted by models.

关键词： thermal structural thick

Spectral selectivity in infrared thermal detection

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Light(Science & Applications) 2012年第1期1卷 56-66页

作者： Joseph J Talghader Anand S Gawarikar ryan p Shea Electrical and Computer Engineering University of MinnesotaMinneapolisMNUSA

A review is made of the physics and technology of spectrally selective thermal detectors,especially those operating at non-cryogenic *** background radiation noise fluctuations are rederived for arbitrary spectral *** absorption due to phonons and free carriers is discussed followed by a review of published works on artificial infrared absorption materials such as patterned grids,nanoparticles,plasmonic structures,metamaterials and ***,the literature of the spectral characteristics of broadband thermal detectors and spectrally selective thermal detectors is ***,the authors speculate on the directions that future research and development in the area will take regarding architectures,sensitivity and spectral characteristics.

关键词： infrared detectors infrared materials radiation noise thermal detectors

A WEpp-Water Quality model for simulating nonpoint source pollutants in nonuniform agricultural hillslopes:Model development and sensitivity

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International Soil and Water Conservation Research 2023年第3期11卷 455-469页

作者： ryan pMcGehee Dennis CFlanagan Bernard AEngel Department of Agricultural and Biological Engineering Purdue University225 South University StreetWest LafayetteIN47907USA DA-Agricultural Research Service National SoilErosion Research Laboratory275 South Russell StreetWest LafayetteIN4797USA

The Water Erosion prediction project(WEpp)model code was modified extensively to support the simulation of nonpoint source(NpS)pollutant sourcing and transport in nonuniform hillslopes based on NpS science from the Soil and Water Assessment Tool(SWAT).This was accomplished utilizing WEpp's overland flow element(OFE)in place of SWAT's hydrologic response unit(HRU)construct which enabled more physically plausible routing within a *** addition,several improvements to the NpS code base were *** include:free-source format,modern-Fortran conventions,minor enhancements to NpS model science,and code *** manuscript documents all model development activities,presents a comparison of relevant WEpp and WEpp-WQ code bases,and performs a local sensitivity analysis of the final model code for the most important input parameters and *** results indicated that the model performed as expected according to its design and provided important insights for potential subsequent validation studies.

关键词： WEpp SWAT WEpp-WQ Water quality Nonpoint Sensitivity