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1999

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Articles 1021 - 1050 of 1307

Full-Text Articles in Engineering

Liquefaction Of Silts And Silt-Clay Mixtures, Tianqiang Guo, Shamsher Prakash Jan 1999

Liquefaction Of Silts And Silt-Clay Mixtures, Tianqiang Guo, Shamsher Prakash

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Low plasticity silts and silty clays occur extensively in the central United States. For evaluating their liquefaction potential during an earthquake, no guidelines are available based on their density, void ratio, plasticity index, standard penetration values, or any other simple soil property. Their liquefaction behavior is not properly understood at present and is often confused with that of sand-silt mixtures. Pore water pressures and liquefaction in silt and silt-clay mixtures are discussed, and the influences of plasticity index on their cyclic strength are reviewed critically. It is concluded that considerable additional work is needed to fully understand the liquefaction behavior …


Design Considerations And Thermodynamic Feasibility Study Of A Meso-Scale Refrigerator, Nabil Shovon Ashraf Jan 1999

Design Considerations And Thermodynamic Feasibility Study Of A Meso-Scale Refrigerator, Nabil Shovon Ashraf

Retrospective Theses and Dissertations

Recent advances in micro-fabrication technology have ushered a new era in miniaturization of chemical, environmental and energy systems. This foreseeable trend towards miniaturization in chemical, environmental and mechanical systems is expected to revolutionize the ways the human life is being perceived today. The high volume and mass reproducibility is seen as the striking aspect of micro-fabrication based miniature systems, offering economies far exceeding than the economies of scale obtained in large plants. The focus of this thesis work is directed at the thermodynamic feasibility and preliminary prototype design for a meso-scale refrigerator. Miniaturization to sub-centimeter domain will enable configuring these …


Models In Manual Materials Handling, M. M. Ayoub, Jeffrey C. Woldstad Jan 1999

Models In Manual Materials Handling, M. M. Ayoub, Jeffrey C. Woldstad

Department of Industrial and Management Systems Engineering: Faculty Publications

The ergonomics approach to manual materials handling (MMH) tasks defines a Man-Task-Environment System. A generally accepted means of minimizing MMH related injuries is to design MMH tasks so that the demands of the tasks are less than the capacities of the individuals performing these tasks. Task design is dependent, in part, on the availability of comparable data for task demands and worker capacities. The generation of the appropriate data is dependent, in part, on being able to identify the pertinent capacity parameters of manual materials handling activities.

In the past, a substantial effort has been directed at determining ‘safe’ lifting …


Remedy Selection For Cleanup Of Uncontrolled Waste Sites, Paul D. Bennett, Brad Brumbach, Tyrone W. Farmer, Preston L. Funkhouser Iv, Allen W. Hatheway Jan 1999

Remedy Selection For Cleanup Of Uncontrolled Waste Sites, Paul D. Bennett, Brad Brumbach, Tyrone W. Farmer, Preston L. Funkhouser Iv, Allen W. Hatheway

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Selection of remedy for uncontrolled hazardous waste sites involves comparisons of various technological approaches for minimization of threats and achievement of cleanup action levels. Approaches specified in the Comprehensive Environmental Response, Compensation and Liability Act (SUPERFUND Law) National Contingency Plan (40 CFR 300) are broadly labeled as actions, alternatives, and technologies. We have found considerable perplexity in denoting the rank-hierarchy of these approaches and have developed a classification system for dealing with the totality of available measures for consideration in selection of remedy.


Stage-Discharge Relations On The Middle Mississippi River, Jerome A. Westphal, D. B. Thompson, Glendon Taylor Stevens, C. N. Strauser Jan 1999

Stage-Discharge Relations On The Middle Mississippi River, Jerome A. Westphal, D. B. Thompson, Glendon Taylor Stevens, C. N. Strauser

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Based on measurements made on the Middle Mississippi River during the 1993 flood, stage-discharge relations for the rating curve are not single-valued. Analyses of these data suggest that the range of flow rates at a given stage is larger than that attributable to measurement replication error alone. Patterns of stage-discharge measurements also imply a tendency toward hysteresis. However, neither changes in stage nor changes in flow rate correlate with short-term scour and fill at gauging sites.


Natural Treatment And On-Site Processes, Kevin D. White, Joel Gerard Burken Jan 1999

Natural Treatment And On-Site Processes, Kevin D. White, Joel Gerard Burken

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The Natural Treatment Systems, Which is Divided into Land-Treatment, Wetland, Aquatic, Onsite and Small Community, and Phytoremediation Systems, Are Discussed. This Include the Free Water Surface Constructed Wetlands, Subsurface Flow Constructed Wetlands, Vertical Flow Constructed Wetlands,ponds, Floating Aquatic Plant Systems, Solar Aquatic Systems, Small Treatment Systems, and In-Ground Disposals.


Unbound Pavement Base Courses: Parallel Study Of Stiffness And Drainage Characteristics, Moussa Issa Jan 1999

Unbound Pavement Base Courses: Parallel Study Of Stiffness And Drainage Characteristics, Moussa Issa

Doctoral Dissertations

The purpose of this project was to study the effects of fines (minus #4 sieve) on permeability and stiffness characteristics of unbound base materials and to propose an optimumgradation that will satisfy these two parameters. One type of highway base material--crushed limestone--was used in the study. A total of 75 laboratory tests were conducted and distributed--25 respectively on permeability, resilient modulus and unconfined compression. The permeability test data were collected using a low-head permeameter. The resilient modulus and unconfined compression test data were collected by the mean of the MTS (Machine Testing System) with a load cell capacity of 22-kips. …


Transition Criteria - From A Pit To A Crack, Tarun Goswami, David W. Hoeppner Jan 1999

Transition Criteria - From A Pit To A Crack, Tarun Goswami, David W. Hoeppner

Biomedical, Industrial & Human Factors Engineering Faculty Publications

A brief review of pitting, which is a localized corrosion process resulting from pitting and fatigue interaction has been conducted in this paper. The transition of a pit to a crack is a very important phenomenon occurring under PCF conditions. Various theories for transition of a pit to a crack were examined within the limits of present understanding and limitations of the models. The transition of a pit to a crack was also discussed for a variety of pit shapes utilizing the pit aspect ratios, defect size and linear elastic fracture mechanics, crack tip characterizing parameters such as Mode I …


The Presence Of Edge Contact And Its Influence On The Debonding Of Patched Panels, Anette M. Karlsson, W. J. Bottega Jan 1999

The Presence Of Edge Contact And Its Influence On The Debonding Of Patched Panels, Anette M. Karlsson, W. J. Bottega

Mechanical Engineering Faculty Publications

A formulation is presented which accounts for configurations of debonding patched cylindrical panels for which the edge of the debonded segment of the patch maintains sliding contact with the corresponding base structure. The formulation is incorporated with that which accounts for configurations for which a contact zone is present and for which no contact between the debonded segments of the patch and base structure occurs during debonding. Analyses are performed for two types of loading conditions: Applied circumferential tension and applied internal pressure. Results of numerical simulations based on analytical solutions of the problems of interest are presented in the …


Hardware-Software Co-Verification In An Undergraduate Laboratory, Hardy J. Pottinger, Daryl G. Beetner Jan 1999

Hardware-Software Co-Verification In An Undergraduate Laboratory, Hardy J. Pottinger, Daryl G. Beetner

Electrical and Computer Engineering Faculty Research & Creative Works

Skills in hardware-software co-design are quickly becoming critical to product development in high-technology computer industries. Systems-on-silicon typically include a considerable amount of software as well as custom hardware and are increasingly difficult to develop using traditional techniques. To satisfy a growing demand in industry, students in electrical Engineering; computer Engineering; and computer science should be introduced to concepts of hardware-software co-design at the undergraduate level. This paper examines a new laboratory at the University of Missouri-Rolla in which students in Electrical and Computer Engineering are exposed to modern system design concepts through the use of hardware-software co-simulation. Key tools used …


Microwave Oscillator With The Shielded Dielectric Resonator, Sergey Kharkovsky, A. E. Kogut, V. K. Komeenkov, V. I. Lutsenko Jan 1999

Microwave Oscillator With The Shielded Dielectric Resonator, Sergey Kharkovsky, A. E. Kogut, V. K. Komeenkov, V. I. Lutsenko

Electrical and Computer Engineering Faculty Research & Creative Works

A Gunn oscillator with partially shielded hemidisk quasioptical resonator is investigated experimentally in this paper. The investigations of the generation characteristics of oscillations by the semiconductor diode in this resonator are carried out for the different radial co-ordinates of the oscillator active element. The advantages of the investigated oscillator in comparison with the oscillator with an open dielectric resonator are shown


Predictive Head Tracking For Virtual Reality, Donald C. Wunsch, Emad W. Saad, T. P. Caudell Jan 1999

Predictive Head Tracking For Virtual Reality, Donald C. Wunsch, Emad W. Saad, T. P. Caudell

Electrical and Computer Engineering Faculty Research & Creative Works

In virtual reality (VR), head movement is tracked through inertial and optical sensors. Computation and communication times result in delays between measurements and updating of the new frame in the head mounted display(HMD). These delays result in problems, including motion sickness. We use recurrent and time delay neural networks to predict the head location and use it to calculate the new frame. A predictability analysis is used in designing the prediction system


High Breakdown Strength, Multilayer Ceramics For Compact Pulsed Power Applications, Wayne Huebner, Brian L. Gilmore, Shi C. Zhang, Mike L. Krogh, B. C. Schultz, R. C. Pate, L. F. Rinehart, J. M. Lundstrom Jan 1999

High Breakdown Strength, Multilayer Ceramics For Compact Pulsed Power Applications, Wayne Huebner, Brian L. Gilmore, Shi C. Zhang, Mike L. Krogh, B. C. Schultz, R. C. Pate, L. F. Rinehart, J. M. Lundstrom

Materials Science and Engineering Faculty Research & Creative Works

Advanced ceramics are being developed for use in large area, high voltage devices in order to achieve high specific energy densities (greater than 10^6/ J/m^3/) and physical size reduction. Initial materials based on slip cast TiO2 exhibited a high bulk breakdown strength (BDS greater than 300 kV/cm) and high permittivity with low dispersion (epsilon approximately equal to 100). However, strong area and thickness dependencies were noted. To increase the BDS, multilayer dielectric compositions are being developed based on glass/TiO2 composites. The addition of glass increases the density (approximately equal to 99.8% theoretical), forms a continuous grain boundary phase, and also …


Modeling The Dielectric Response And Relaxation Spectra Of Relaxor Ferroelectrics, Huh Tswen Lin, David C. Van Aken, Wayne Huebner Jan 1999

Modeling The Dielectric Response And Relaxation Spectra Of Relaxor Ferroelectrics, Huh Tswen Lin, David C. Van Aken, Wayne Huebner

Materials Science and Engineering Faculty Research & Creative Works

A multi-Debye relaxation model that is based upon the Boltzmann superposition principle has been used to determine the frequency-dispersion behavior of Pb (Mg1/3-Nb2/3)O3 (PMN) and Pb0.88La0.08 (Zr0.65Ti0.35) O3 (PLZT 8/65/35) relaxor ferroelectrics. For PMN, relaxation times on the order of seconds contribute to the dispersive character of the dielectric properties. A defect-relaxation mechanism that involves Mg cation hopping in a structure that is composed of interpenetrating 〈111〉 chains of ordered Pb (Mg1/2Nb1/2) O3 is proposed for PMN. Motion of the Mg cations …


Analog Hardware Implementation Of Continuous-Time Adaptive Filter Structures, John G. Harris, Jui Kuo Juan, Jose C. Principe Jan 1999

Analog Hardware Implementation Of Continuous-Time Adaptive Filter Structures, John G. Harris, Jui Kuo Juan, Jose C. Principe

Electrical and Computer Engineering Faculty Research & Creative Works

We have implemented a four-tap adaptive filter in a continuous-time analog VLSI circuit. Since an ideal delay is impossible to implement in continuous-time hardware, we implemented the delay line as a cascade of low-pass filters (called the gamma filter). Since many years of research in our lab has shown that the gamma filter outperforms the ideal delay line for a wide range of applications, the gamma filter should not be considered merely a crude approximation of the ideal delay line. We show measured results from an analog chip that solves the problem of system identification-identifying an unknown linear circuit from …


Frequency Domain Robustness Analysis Of Hopfield And Modified Hopfield Neural Networks, Jie Shen, S. N. Balakrishnan Jan 1999

Frequency Domain Robustness Analysis Of Hopfield And Modified Hopfield Neural Networks, Jie Shen, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A variant of Hopfield neural network, called the modified Hopfield network, is formulated in this study. This class of networks consists of parallel recurrent networks which have variable dimensions that can be changed to fit the problem under consideration. It has a structure to implement an inverse transformation that is essential for embedding optimal control gain sequences. Equilibrium solutions of this network are discussed. The robustness of this network and the classical Hopfield network are carried out in the frequency domain using describing functions


Online Identification And Control Of Aerospace Vehicles Using Recurrent Networks, Zhenning Hu, S. N. Balakrishnan Jan 1999

Online Identification And Control Of Aerospace Vehicles Using Recurrent Networks, Zhenning Hu, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Methods for estimating the aerospace system parameters and controlling them through two neural networks are presented in this study. We equate the energy function of Hopfield neural network to integral square of errors in the system dynamics and extract the parameters of a system. Parameter convergence is proved. For control, we equate the equilibrium status of a "modified" Hopfield neural network to the steady state Riccati solution with the system parameters as inputs. Through these two networks, we present the online identification and control of an aircraft using its nonlinear dynamics.


Stability Analysis Of Nonlinear Machining Force Controllers, Robert G. Landers, Yen-Wen Lu Jan 1999

Stability Analysis Of Nonlinear Machining Force Controllers, Robert G. Landers, Yen-Wen Lu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Model parameters vary significantly during a normal operation, thus, adaptive techniques have predominately been used. However, model-based techniques that carefully account for changes in the force process have again been examined due to the reduced complexity afforded by such techniques. In this paper, the effect of model parameter variations on the closed-loop stability for two model-based force controllers is examined. It was found that the stability boundary in the process parameter space can be exactly determined for force control systems designed for static force processes. For force control systems designed for first-order force processes, it was found that the stability …


X-Ray Absorption, Neutron Diffraction, And Mössbauer Effect Studies Of Mnzn-Ferrite Processed Through High-Energy Ball Milling, D. J. Fatemi, V. G. Harris, Mingxing Chen, Satish K. Malik, William B. Yelon, Gary J. Long, Amitabh Mohan Jan 1999

X-Ray Absorption, Neutron Diffraction, And Mössbauer Effect Studies Of Mnzn-Ferrite Processed Through High-Energy Ball Milling, D. J. Fatemi, V. G. Harris, Mingxing Chen, Satish K. Malik, William B. Yelon, Gary J. Long, Amitabh Mohan

Physics Faculty Research & Creative Works

MnZn-ferrite has been prepared via high-energy ball milling of elemental oxides MnO, ZnO, and α-Fe2O3. Neutron diffraction measurements suggest a high density of vacancies in a spinel structure. The spinel phase appears to comprise 99.8 wt % of the material in the sample milled for 40 h, with the remainder attributable to unreacted α-Fe2O3. The x-ray absorption near-edge structure was analyzed to provide an understanding of the charge state of the constituent Fe ions. This analysis reveals about 2/3 of Fe cations to be trivalent, increasing to about 3/4 after a 5 …


A Distributed Algorithm For The Classification Of Images On A Network Of Workstations, S. R. Subramanya Jan 1999

A Distributed Algorithm For The Classification Of Images On A Network Of Workstations, S. R. Subramanya

Electrical and Computer Engineering Faculty Research & Creative Works

Image databases require content-based queries and retrievals. Fast and accurate retrievals for user queries depend on efficient indexing and searching schemes. The classification of images into different categories (classes) is an important task which facilitates the indexing and searching process. The classification of huge amounts of image data place enormous demands on computational requirements. Network of workstations (NOWs, also sometimes called clusters) are a cost-effective way of providing the much-needed computational power in such applications. This paper presents a distributed scheme for the classification of images in an image database, using a network of workstations. The results of the classification …


Liquid Holdup Measurement Techniques In Laboratory High Pressure Trickle Bed Reactors, Muthanna H. Al-Dahhan, Wes Highfill Jan 1999

Liquid Holdup Measurement Techniques In Laboratory High Pressure Trickle Bed Reactors, Muthanna H. Al-Dahhan, Wes Highfill

Chemical and Biochemical Engineering Faculty Research & Creative Works

Three Different Techniques, Which Are Tracer, Drainage and Weighing Methods, Are Used to Measure Liquid Holdup in a Laboratory Trickle-Bed Reactor Operated under High Pressure. the Holdup Measurements Are Compared to Determine the Applicability of These Methods at High Pressure Operation. It Was Found that Tracer and Drainage Techniques Give Comparable Values for the Total Liquid Holdup. Although Several Investigators Recommended the Weighing Method over the Others based on their Experiments Performed at Atmospheric Conditions, It Was Found that the Weighing Method Failed to Measure Liquid Holdup Properly at High Pressure Operation.


Thermal Characterization Of Pmma Thin Films On Silica Using Modulated Differential Scanning Calorimetry, Crystal E. Porter, Frank D. Blum Jan 1999

Thermal Characterization Of Pmma Thin Films On Silica Using Modulated Differential Scanning Calorimetry, Crystal E. Porter, Frank D. Blum

Chemistry Faculty Research & Creative Works

The number of studies of thin polymer films has increased over recent years as technological processes incorporate the use of nanomaterials. An enhanced understanding of these films would enable us to predict bound-polymer behavior and thus improve the efficiency of processes and the quality of products. This is especially true as the thickness of the films approach molecular dimensions. The glass transition temperature of a polymer is one of the most important properties for characterization because it indicates how the polymer might perform macroscopically. when a polymer is confined, such as one the surface of a substrate, its behavior is …


Mechanism Of Interaction Of Asphalt Cement With Crumb Rubber Modifier, Magdy Abdelrahman, Samuel Carpenter Jan 1999

Mechanism Of Interaction Of Asphalt Cement With Crumb Rubber Modifier, Magdy Abdelrahman, Samuel Carpenter

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The nature of the interaction process between asphalt cement and crumb rubber modifier (CRM) has not been fully understood. Two main types of mechanisms that affect the produced binder properties are reported: particle swelling and degradation (devulcanization and depolymerization). These mechanisms occur as the binder is subjected to different combinations of interaction time and temperature. Insight into the mechanisms by which the interaction between the two materials takes place through monitoring the changes in the rheological parameters of the binder is provided. The effects of the interaction process variables, time and temperature, are explained. The effect of CRM properties, including …


Nonuniformity Correction Of Infrared Image Sequences Using The Constant-Statistics Constraint, John G. Harris, Yu Ming Chiang Jan 1999

Nonuniformity Correction Of Infrared Image Sequences Using The Constant-Statistics Constraint, John G. Harris, Yu Ming Chiang

Electrical and Computer Engineering Faculty Research & Creative Works

Using clues from neurobiological adaptation, we have developed the constant-statistics (CS) algorithm for nonuniformity correction of IRFPA's and other imaging arrays. The CS model provides an efficient implementation that can also eliminate much of the ghosting artifact that plagues all scene-based nonuniformity correction (NUC) algorithms. The CS algorithm with deghosting is demonstrated on synthetic and real infrared (IR) sequences and shown to improve the overall accuracy of the correction procedure.


Hypersonic Drag And Heat Transfer Reduction Using A Forward Facing Jet, Benjamin Meyer, Harlan F. Nelson, David W. Riggins Jan 1999

Hypersonic Drag And Heat Transfer Reduction Using A Forward Facing Jet, Benjamin Meyer, Harlan F. Nelson, David W. Riggins

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A two-dimensional numerical study of the effects of a forward-facing jet located at the stagnation point of a blunt body on wave drag, heat transfer, and skin friction drag is presented for Mach 6.5 flow at 30 km altitude. The full Navier-Stokes equations are used with variable viscosity and thermal conductivity. It is shown that upstream injection can significantly modify the flow field. If the jet conditions are chosen properly, large reductions in drag and heat transfer can be obtained resulting in possible increases in the volumetric efficiency and static stability of aircraft and reductions in heating protection requirements for …


Functional Interdependence And Product Similarity Based On Customer Needs, Daniel A. Mcadams, Robert B. Stone, Kristin L. Wood Jan 1999

Functional Interdependence And Product Similarity Based On Customer Needs, Daniel A. Mcadams, Robert B. Stone, Kristin L. Wood

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, related product functions are determined for a group of approximately 70 consumer products. Using customer need data, a new matrix approach is introduced to identify these relationships. Techniques are then created for determining product similarity. These techniques are clarified and validated through three case studies, including beverage brewers and material-removal products. The results of these case studies are argued to have significant impact on design-by-analogy procedures, benchmarking methods, mass customization strategies and modular design. The paper concludes with a discussion of applications and related procedures for product development.


Application Of Composite Gyromagnetic Materials For Absorbing Radiation Produced By Microwave Oven, Marina Koledintseva, Alexander A. Kitaytsev, V. A. Konkin, V. P. Cheparin, Andrey A. Shinkov Jan 1999

Application Of Composite Gyromagnetic Materials For Absorbing Radiation Produced By Microwave Oven, Marina Koledintseva, Alexander A. Kitaytsev, V. A. Konkin, V. P. Cheparin, Andrey A. Shinkov

Electrical and Computer Engineering Faculty Research & Creative Works

Composite gyromagnetic radioabsorbing material (RAM) on the basis of polycrystalline hexagonal ferrites is elaborated for the suppression of unwanted radiation produced by microwave ovens (MWO). Results of laboratory investigation of this material application in the MWO having a magnetron source of microwave radiation are represented.


Kentucky Traffic Accident Facts 1999 Report, Kentucky Transportation Center, Kentucky State Police Jan 1999

Kentucky Traffic Accident Facts 1999 Report, Kentucky Transportation Center, Kentucky State Police

Kentucky Transportation Center Research Report

KENTUCKY’S TRAFFIC ACCIDENT FACTS report for 1999 is based on accident reports submitted to the Accident Unit housed in the Kentucky State Police Information Services Branch, Records Section. As required by Kentucky Revised statutes 189.635, “every law enforcement agency whose officers investigate a vehicle accident of which a report must be made...shall file a report of the accident...within ten days after investigation of the accident upon forms supplied by the bureau.” The stated purpose of this requirement is to utilize data on traffic accidents” for such purposes as will improve the traffic safety program in the Commonwealth.” Data contained in …


Direct Current High-Pressure Glow Discharges, Robert H. Stark, Karl H. Schoenbach Jan 1999

Direct Current High-Pressure Glow Discharges, Robert H. Stark, Karl H. Schoenbach

Bioelectrics Publications

Stabilization and control of a high-pressure glow discharge by means of a microhollow cathode discharge has been demonstrated. The microhollow cathode discharge, which is sustained between two closely spaced electrodes with openings of approximately 100 μm diam, serves as plasma cathode for the high-pressure glow. Small variations in the microhollow cathode discharge voltage generate large variations in the microhollow cathode discharge current and consequently in the glow discharge current. In this mode of operation the electrical characteristic of this system of coupled discharges resembles that of a vacuum triode. Using the microhollow cathode discharge as plasma cathode it was possible …


Direct Current Glow Discharges In Atmospheric Air, Robert H. Stark, Karl H. Schoenbach Jan 1999

Direct Current Glow Discharges In Atmospheric Air, Robert H. Stark, Karl H. Schoenbach

Bioelectrics Publications

Direct current glow discharges have been operated in atmospheric air by using 100 μm microhollow cathode discharges as plasma cathodes. The glow discharges were operated at currents of up to 22 mA, corresponding to current densities of 3.8 A/cm2 and at average electric fields of 1.2 kV/cm. Electron densities in the glow are in the range from 1012 to 1013  cm−3. Varying the current of the microhollow cathode discharge allows us to control the current in the atmospheric pressure glow discharge. Large volume atmospheric pressure air plasmas can be generated by operating microhollow cathode discharges …