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Spatiotemporal characteristics of positive cloud-to-ground lightning discharges and bidirectional leader of the lightning

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Science China Earth Sciences 2006年第2期49卷 212-224页

作者： Krehbiel Paul new mexico institute of mining and technology Socorro New Mexico 87801 USA

The three-dimension spatiotemporal development characteristics of positive cloud-to- ground (CG) lightning discharges have been analyzed by using the data measured by the lightning mapping array system with high time and space resolution. The results indicate that a positive CG lightning discharge can be divided into three stages based on the characteristics of its development. The first stage is discharge process in cloud with a long duration preceding the return stroke. This process with an average of 370 ms propagated at velocity of 105 m/s and produced intensive radiation with a magnitude equal to that of the negative leader. During this stage, the lightning channels de-veloped horizontally in the positive charge region with few branches as the negative polarity break-down. During the stage after the return stroke of the positive CG lightning, the lightning channels propagated at velocity of 2 times faster than that before the return stroke. This stage involved lots of positive fast impulses and corresponded to the continuing current process producing less and dis-persed radiation points and more intensive radiation powers. During the final stage of the positive CG lightning, the lightning channels developed at velocity equal to that before the return stroke and the radiation points appeared mainly at the ends of channel. The spatiotemporal development character-istics of the positive CG lightning are very different from that of the negative CG lightning. All of the radiation points of the positive CG lightning appeared in the positive charge region of cloud. Little or no radiation was detected during the positive leader just before the return stroke. The duration of the positive CG lightning was an average of 730 ms. The positive CG lightning discharges with lasting time of 500―600 ms were 43%. 90% of the positive CG lightning discharges involved one return stroke, the most return stroke number being four. The current of the return stroke was an average of 36.5

关键词： positive CG lightning, radiation characteristics, bidirectional leader.

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Quantifying the thermal damping effect in underground vertical shafts using the nonlinear autoregressive with external input(NARX) algorithm

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International Journal of mining Science and technology 2019年第2期29卷 255-262页

作者： Pedram Roghanchi Karoly C.Kocsis Mineral Engineering Derpartment New Mexico Institute of Mining and Technology mining Engineering Derpartment University of Nevada

As air descends the intake shaft, its infrastructure, lining and the strata will emit heat during the night when the intake air is cool and, on the contrary, will absorb heat during the day when the temperature of the air becomes greater than that of the strata. This cyclic phenomenon, also known as the "thermal damping effect" will continue throughout the year reducing the effect of surface air temperature variation. The objective of this paper is to quantify the thermal damping effect in vertical underground airways. A nonlinear autoregressive time series with external input(NARX) algorithm was used as a novel method to predict the dry-bulb temperature(Td) at the bottom of intake shafts as a function of surface air temperature. Analyses demonstrated that the artificial neural network(ANN) model could accurately predict the temperature at the bottom of a shaft. Furthermore, an attempt was made to quantify typical "damping coefficient" for both production and ventilation shafts through simple linear regression models. Comparisons between the collected climatic data and the regression-based predictions show that a simple linear regression model provides an acceptable accuracy when predicting the Tdat the bottom of intake shafts.

关键词： Underground mining Vertical openings Thermal damping effect Artificial neural network Nonlinear autoregressive with external input(NARX)

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Conceptual design and optimization of a tilt-rotor micro air vehicle

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Chinese Journal of Aeronautics 2019年第2期32卷 369-381页

作者： M.HASSANALIAN R.SALAZAR A.ABDELKEFI Department of Mechanical and Aerospace Engineering New Mexico State University Department of Mechanical Engineering New Mexico Institute of Mining and Technology

The conceptual design and optimization of a tilt-rotor Micro Air Vehicle(MAV) for a well-defined mission are performed. The objective of this design cycle is to decrease the design time in order to efficiently create a functional tilt-rotor drone. A flight mission is firstly defined for a tiltrotor MAV performing hovering and cruise flight scenarios. Secondly, a complex wing shape is chosen and modeled in order to determine the final shape. The initial shape is scaled in order to acquire an arbitrary wingspan of one meter. For the specific area and wingspan, the aspect ratio of the designed wing shape is found to be equal to 2.32. Thirdly, a constraint analysis of the MAV is performed by using an energy balance analysis for six different flight scenarios. This analysis yields the required power loading and wing loading. Fourthly, the weight of the vehicle is estimated using both statistical and computational methods. After estimating the total weight and the wing loading of the MAV, the surface of the wing is determined, yielding a final wingspan of 0.76 m. Subsequently, considering the total weight of the designed MAV, the needed lift coefficient is ***, using the lift coefficient in conjunction with XLFR5, a batch of airfoils is selected and analyzed to evaluate the aerodynamic coefficients of the wing with each airfoil. This analysis ultimately leads to the optimum airfoil being selected. Finally, design of the fuselage and tail, internal components selection, and servo-mechanisms design are carried out prior to a stability analysis. All these proposed steps are needed to design efficient and functional tilt-rotor MAVs.

关键词： Aerodynamic analysis Sizing Tilt-rotor MAV VTOL Stability

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Effects of Avian Wings Color Patterns on Their Flight Performance:Experimental and Computational Studies

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Journal of Bionic Engineering 2023年第2期20卷 683-710页

作者： Ahmed Aboelezz Brenden Herkenhoff Mostafa Hassanalian Department of Mechanical Engineering New Mexico Institute of Mining and TechnologySocorroNM87801USA

There are many theories behind the colors of a bird’s *** of these theories point to the color’s purpose to attract mates and hide from *** recent investigations concluded that the dark colors of birds help in reducing the drag force during flight.A new theory is presented in the current research,which states that a bird's dark color not only reduces the drag,but the color pattern also improves the overall flight performance,and each color pattern has a different type of flight performance *** difference in improvement is a result of variation in hot and cold surfaces on the bird skin as a result of the variation between light and dark feather *** prove this new theory,thermal images were captured of real bird wings under the effect of infrared ***,a novel wind tunnel wing with the ability to adjust the temperature in desired locations and patterns on the wing’s surface was manufactured and tested to evaluate the effect of aerodynamics forces as a function in the surface temperature and the hot–cold *** collected data from this wing showed potential flight efficiency improvements of 20%,comparing the lift-to-drag ratio for specific heating cases,which could increase the flight *** considering lift and drag,there were specific heating cases with corresponding angles of attack in which these parameters improved by up to 20%and 7%,*** heating cases could increase the lift at a low angle of attack,which is helpful in cruise flight performance,while some cases could increase the maximum lift coefficient by 6%.This is very helpful in lowering stall and the minimum flight ***,some cases could increase the lift-to-drag ratio,which led to an increase in the flight *** better understand the effect of the various patterns,computational fluid dynamics(CFD)simulations were conducted on the *** new theory was proved based on the CFD results and verified through the success

关键词： Aerodynamic loads CFD Drag Heated boundary layer Surface temperature

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Polymer flooding: Current status and future directions

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Petroleum Science 2023年第2期20卷 910-921页

作者： R.S.Seright Dongmei Wang new mexico institute of mining and technology SocorroNMUSA University of North Dakota Grand ForksNDUSA

This review presents our perspective on the factors that have brought polymer flooding to its current state. Insights are provided on why HPAM is the dominant polymer used as well as what is needed to make alternative polymers and mobility-control methods viable. Explanation is given for why large polymer banks are needed for polymer flooding, and design of the injected polymer viscosity is detailed for cases with/without crossflow. The role of fractures and horizontal wells are discussed for improving injectivity and extending polymer flooding to recover oils with viscosities as high as 10,000 cP. Operational improvements are described to minimize mechanical and oxidative stability to allow HPAM polymers to be viable to 70 °C and ATBS polymers to 120 °C. Key factors affecting polymer retention are summarized. The paper points out unresolved issues and future directions for polymer flooding.

关键词： Polymer flooding Reservoir sweep improvement

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A Lightweight Anonymous Device Authentication Scheme for Information-Centric Distribution Feeder Microgrid

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Computers, Materials & Continua 2021年第11期69卷 2141-2158页

作者： Anhao Xiang Jun Zheng Department of Computer Science and Engineering New Mexico Institute of Mining and TechnologySocorro87801NMUSA

Distribution feeder microgrid(DFM)built based on existing distributed feeder(DF),is a promising solution for modern *** contains a large number of heterogeneous devices that generate heavy network traffice and require a low data delivery *** information-centric networking(ICN)paradigm has shown a great potential to address the communication requirements of smart ***,the integration of advanced information and communication technologies with DFM make it vulnerable to cyber *** authentication of grid devices is essential for preventing unauthorized accesses to the grid network and defending against cyber *** this paper,we propose a new lightweight anonymous device authentication scheme for DFM supported by named data networking(NDN),a representative implementation of *** perform a security analysis to show that the proposed scheme can provide security features such as mutual authentication,session key agreement,defending against various cyber attacks,anonymity,and resilience against device capture *** security of the proposed scheme is also formally verified using the popular AVISPA(Automated Validation of Internet Security Protocols and Applications)*** computational and communication costs of the proposed scheme are *** results demonstrate that the proposed scheme achieves significantly lower computational,communication and energy costs than other state-of-the-art schemes.

关键词： Mutual authentication information-centric networking named data networking distribution feeder microgrid smart devices AVISPA security

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Water shutoff and conformance improvement: an introduction

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Petroleum Science 2021年第2期18卷 450-478页

作者： Randy Seright Bergit Brattekas new mexico institute of mining and technology SocorroNMUSA Department of Physics and technology University of BergenBergenNorway

This paper provides an introduction to the topic of water shutoff and conformance improvement. After indicating the volumes of water produced during oilfield operations, a strategy is provided for attacking excess water production problems. Problem types are categorized, typical methods of problem diagnosis are mentioned, and the range of solutions is introduced for each problem type. In the third section of the paper, the concept of disproportionate permeability reduction is introduced—where polymers and gels may reduce permeability to water more than to oil or gas. When and where this property is of value is discussed. The fourth section describes the properties of formed gels as they extrude through fractures and how those properties can be of value when treating conformance problems caused by fractures. Section 5 covers the efficiency with which gels block fractures after gel placement—especially, the impact of fluids injected subsequent to the gel treatment.

关键词： Water shutoff Conformance improvement Reservoir sweep improvement

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Polarity inverted intracloud discharges and electric charge structure of thunderstorm

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Chinese Science Bulletin 2002年第20期47卷 1725-1729,1761-1763页

作者： ZHANG Yijun P.R.Krehbiel LIU Xinsheng Cold and Arid Regions Environmental and Engineering Research institute Lanzhou 730000China new mexico institute of mining and technology SocorroNew MexicoUSA

The three-dimensional spatial and temporal development of impulsive VHF radiation events during lightning discharges has been analyzed based on the data measured by the lightning mapping array (LMA) system with high space and time resolution. The results indicate that intracloud discharges in the thunderstorm with a normal tripole charge structure occur not only between the upper positive and middle main negative charge region, but also with inverted polarity between the lower positive and middle main negative charge region. The polarity-inverted discharge originates from the middle negative charge and propagates downward to the lower positive region, where then the discharge develops horizontally. The characteristics of the discharge are similar to that of normal intracloud discharge except the polarity opposite. The results further confirmed the existence of the lower positive charge region involved in the lightning discharge. It was also found that the inverted charge structure opposite to the

关键词： intracloud discharge charge structure of thunderstorm polarity inverted discharge.

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Time series analysis of mantle cycles Part Ⅰ:Periodicities and correlations among seven global isotopic databases

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Geoscience Frontiers 2019年第4期10卷 1305-1326页

作者： Stephen J. Puetz Kent C. Condie Progressive Science institute HonoluluHI96815USA new mexico institute of mining and technology SocorroNM87801USA

In this study,seven isotopic databases are presented and analyzed to identify mantle and crustal episodes on a global scale by focusing on periodicity ranging from 70 to 200 million years(Myr).The databases are the largest,or among the largest,compiled for each type of data-with an objective of finding some samples from every region of every continent,to make each database as global as conceivably *** databases contain zircon Lu/Hf isotopic data,whole-rock Sm/Nd isotopic data,U/Pb detrital zircon ages,U/Pb igneous zircon ages,U/Pb non-zircon ages,whole-rock Re/Os isotopic data,and large igneous province *** I of this study focuses on the periodicities of age histograms and geochemical averages developed from the seven databases,via spectral and cross-correlation *** physical cycles often propagate in exact integer multiples of a fundamental cycle,referred to as *** tests show that harmonic geological cycles of^93.5 and^187 Myr have persisted throughout terrestrial history,and the cyclicities are statistically significant for U/Pb igneous zircon ages,U/Pb detrital zircon ages,U/Pb zircon-rim ages,large igneous province ages,meanεHf(t)for all samples,meanεHf(t)values for igneous-only samples,and relative abundance of mafic *** important,cross-correlation analyses show these seven time-series are nearly synchronous(±7 Myr)with a model consisting of periodicities of 93.5 and 187 ***,the similarities between peaks in the 93.5 and 187 Myr mantle cycles and terminal ages of established and suspected superchrons provide a framework for predicting and testing superchron periodicity.

关键词： Zircon Database Isotope Statistical analysis Spectral analysis Cross correlation

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Refnement of the supercontinent cycle with Hf, Nd and Sr isotopes

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Geoscience Frontiers 2013年第6期4卷 667-680页

作者： Kent C.Condie Richard C.Aster Department of Earth and Environmental Science New Mexico Institute of Mining and Technology Geosciences Department Colorado State University

The combined use of Hf,Nd and Sr isotopes is more useful in understanding the supercontinent cycle than the use of only Hf isotopic data from detrital *** and Nd seawater isotopes,although not as precise as εNd and εHf distributions,also record input from ocean ridge *** detrital zircons where sources cannot be precisely located because of crustal recycling,both the location and tectonic setting often can be constrained for whole-rock Nd isotopic ***,primary zircon sources may not reside on the same continent as derivative detrital zircons due to supercontinent breakup and *** to all of the isotopic studies are geographic sampling biases reflecting outcrop distributions,river system sampling,or geologists,and these may be responsible for most of the decorrelation observed between isotopic *** between 3.5 and 2 Ga based on εHf median values of four detrital zircon databases as well as our compiled εNd database are noisy but uniformly distributed in time,whereas data between 2 and 1 Ga data are more tightly clustered with smaller *** age peaks suggest that both isotopic systems are sampling similar types of *** after 1 Ga and before 3.5 Ga do we see wide variations and significant disagreement between databases,which may partially reflect variations in both the number of sample locations and the number of samples per *** and internal orogens show similar patterns in εNd and εHfwith age suggesting that both juvenile and reworked crustal components are produced in both types of orogens with similar ***,both types of orogens clearly produce more juvenile isotopic signatures in retreating mode than in advancing *** secular changes in εHf and εNd distributions correlate with the supercontinent *** supercontinent breakup is correlated with short-lived decreasing εHf and εNd （≤ 100 Myr） for most supercontinents,there is no isotopic evidence for

关键词： Supercontinent cycle Hf isotopes Nd isotopes Collisional orogens Accretionary orogens

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