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By F Hungerford, T Ren

"Gas management has always been a major concern for the ventilation officer of any gassy mine. With an increase of mining depth and gas content, there is a great demand for the development of in-seam drilling sites where boreholes can be drilled for the pre-drainage of gas prior to longwall operation. The ventilation and gas management in the drilling site therefore becomes a critical component of mine safety. In this study, advanced computational fluid dynamics technology was adopted to investigate the aerodynamics of gas emitting from the drilling site and boreholes during normal drilling and, in the case of a sudden gas inrush, from the borehole. In addition, the impact of different ventilation controls on gas removal in the drilling site was investigated. Modelling results indicate that gas accumulation zones could be formed if the ventilation system fails to deliver sufficient airflow to the drill site, especially when a sudden gas inrush from a borehole occurs. The configurations of brattice, layout of ventilation tubes and the gas emission rate all have a significant effect on the gas distribution. Due to variations in site-specific conditions, it would be desirable to conduct modelling studies to assess the effects and efficiencies of a ventilation design for the varying environment on-site before carrying out drilling practice. CITATION: Ren, T, Hungerford, F and Wang, Z, 2015. Computational modelling studies of ventilation management for underground in-seam drilling sites, in Proceedings The Australian Mine Ventilation Conference, pp 239–250 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 31, 2015

By Laurentiu Nastac, Ruslan Mudryy

"This paper investigates the solidification of cast energetic materials. An active cooling and heating (ACH) technology and a mechanical vibration (MV) technology were applied to achieve unidirectional solidification during casting and to reduce cracks, gas pores, and shrinkage defects. The design parameters of these technologies were developed via Computational Fluid Dynamics (CFD) modeling and thermal stress analysis. Concerning the ACH technology, the number of cooling/heating sections and their temperature profiles and time sequences were optimized based on the thermo-physical properties of the energetic material as well as the riser and mold diameter, thickness and type. The ACH technology will also decrease the thermal stresses during casting of energetic materials and therefore minimize the formation of potential cracks that may form during the casting process. The MV technology will help to remove air entrapped during pouring process and decrease the detrimental gap size between the projectile and the solidified energetic material.IntroductionCasting processes are widely employed in the manufacture of products with intricate shapes and, in particular, in applications where the material of the final product is sensitive to machining. It is especially useful in processing of energetic materials. The cooling conditions applied in the casting process can affect the quality of the final cast in terms of void formation, residual stress distributions, and mold separation. Substantial shrinkage is also observed due to the density change upon solidification [1-3]. Residual stresses are known to be closely related to the formation of cold cracks and hot tears during casting. The formation of a gap between the mold and the cast material is of critical importance due to its deleterious effect on heat removal and on crack formation. In the casting of energetic materials all these defects can significantly impair the detonation velocity, Gurney energy, and insensitive munitions characteristics of the formulation, and lead to catastrophic accidents in explosives handling [ 4-5]. Imposition of carefully controlled cooling condition is thus critical in optimizing the cast quality that could help avoid such destructive effects."

Jan 1, 2013

By J. Abrahams, A. Nesbitt

Over the past half-century, researchers have commented on the complexities of ion-exchange processes, but have been forced to use gross assumptions to simplify the associated mathematics sufficiently for mathematical models to be of practical use, given the available computational power. This paper reviews the development of increasingly complex models as computational power has increased over the past half-century, from the direct application of Fick's Law in 1947, through to today's models requiring finiteelement methods. The assumptions required for and the associated limitations of the various models are presented and the associated computational complexities are discussed. A case study is presented in which a continuous loss of capacity in an acid resin was observed over about sixty cycles of loading and elution. Resin poisoning does not explain this observation. This paper presents the capacity loss data, speculates on possible causes of the phenomenon, discusses why conventional kinetic and equilibrium mechanisms cannot explain it and concludes that the need to develop a more rigorous model is apparent. The significance of this observation is that standard tests done for a new resin application could significantly overestimate the commercial performance of the resin concerned, highlighting the importance of computer simulation in this field of process engineering.

Jan 1, 2005

By Jancar T, de Guzman M M, Matthews B, Tu J. Y

The use of computational simulation to predict the performance of existing equipment or for the design of improved mineral processing equipment will be referred to as Computational Mineral Processing (CMP) in this paper. The emphasis will be on solving the governing equations for liquid solid flows in complex geometric domains to obtain, typically, the three-dimensional distributions of velocity and pressure for the liquid phase and the velocity and concentration for the solid phase. The underlying technology, computational fluid dynamics (CFD), is very well-developed in other industries (aircraft, car and chemical) and forms a vital part of product design and analysis. The subsequent design of improved mineral processing equipment may also involve finite element structural analysis (FESA). Computational fluid dynamics (CFD) and finite element structural analysis (FESA) are part of the generic discipline of Computational Engineering and Science (CES). Ciment and Scherlis (1993) define CES as `The systematic application of computing systems and computational solution techniques to mathematical models formulated to describe and simulate phenomena of scientific and engineering interest'. Increasing computer power (Kaufmann and Smarr, 1993), is a dominant factor determining the rapid growth of industrial utilisation of CES. This increase is happening at both the supercomputer and the workstation level. Indeed, today's typical workstation, a Hewlett-Packard 735, is as powerful as a CDC 7600, the leading supercomputer in 1970. Future computer architectures are expected to become increasingly parallel (Gartner Group, 1990) allowing a sustained performance of a teraflop (a million megaflops) to be achieved well before the Sydney Olympics in the year 2000. It is recognised that the modem development of most disciplines in the physical sciences rests on the three complementary strategies of experimentation, analysis and computational simulation. As the 21st century is approached the volume of computational simulation, both fundamental and applied, is growing dramatically and the role of experimentation is diminishing. In the area of equipment design, CES provides the following advantages over experimental testing and measurement: 1. lead time in design and development is significantly reduced; 2. CES can simulate conditions not reproducible in experimental tests; 3. CES provides detailed and comprehensive information; and 4. CES is more cost-effective and time-efficient. The ultimate benefit for industry is greater productivity and hence greater profitability. The broader issues in relation to CFD are discussed by Fletcher (1993b). In the five- to ten-year time frame, growth in computer power will make it practical to combine CFD and FESA with optimisation procedures to produce a design process that is almost fully computerised. It is expected that fully automatic

Jan 1, 1995

By Ricardo Burdisso, Rahul Kadam, Kyle Schwartz, Marty Johnson

Occupational exposure to hand transmitted vibration (HTV) arises from the hand held powered tools extensively used in the mining and construction industry such as rock drills, chipping hammers, chain saws etc. Regular exposure to HTV is the major cause of a range of permanent injuries to human hands and arms which are commonly referred to as hand-arm vibration syndrome (HAVS). In addition to this, the percussive tools generate overall sound power levels in excess of 110dBA in most cases. Such a high sound power level greatly exceeds the maximum permissible exposure limit (PEL) of organizations such as National Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration (OSHA). Long term occupational exposure to this noise has been diagnosed as the main reason for permanent hearing loss in the operators. It is therefore important to develop an understanding of the mechanisms which lead to these high vibration and sound levels and in order to do this a detailed computational model of a pneumatic chipping hammer has been made. This paper presents a nonlinear computational model of a pneumatic chipping hammer. In order to better understand the dynamics of the chipping hammer, the hammer was subdivided into components that are shown in figure 1 (a) (based on a chipping hammer manufactured by Atlas-Copco). The hammer mainly consisted of a center body, a moving piston and a chisel. Compressed air is used to drive the piston inside of a cylinder and on the downward stroke this piston impacts the chisel to create the hammer effect. The machine has one pneumatic valve and this valve regulates the air supply either to the upper chamber or to the lower chamber. The valve changes according to the relative pressures in the two chambers and the supply pressure. There are also twelve different exhaust ports at two positions along the cylinder labeled upper ports and lower ports. As the piston moves the ports can be closed or open (allowing exhaust). Fundamentally, the computational model was made up of two different sub-models, a fluid model and a structural dynamic model as shown in Figure 3 (a) and (b) respectively. The first sub-model takes into consideration the fluid dynamics of the machine since the hammer is driven by compressed air. Equations for the mass flow rate though bleed orifices (assuming an isentropic process) 1 is used to determine the mass flow into and out of the upper and lower chambers. From this the pressures in the two chambers and consequently the forcing on the piston can be calculated. The second sub-model deals with modeling the structural [ ]

Jan 6, 2006

By A Liu, T Ren

Gas explosion in underground coal workings can pose a serious threat to the safety of mine workers and the entire mine operations. Gas explosion is a very complex thermal-chain reaction in a confined underground environment. Based on combustion and explosion theory, three dimensional (3D) computational models were developed to simulate mine gas explosion flame and overpressure wave propagation in a single entry gateroad in underground coalmines. Six different explosion scenarios were modelled and compared with large scale experimental results and AutoReaGas simulations. Model validations show that the use of shear-stress transport (SST) k-? model together with eddy-dissipation model (EDM) produces good agreement with both experimental and AutoReagas simulation results. Modelling results demonstrated that the changes of temperature versus time can be divided into four stages, ie the initial condition stage, and periods of warm-up, active burning, and burnt-out. Assuming a limited volume of methane is involved in the explosion, the maximum temperature decreases as the distance increases from the explosion point, with the highest temperature reaching about 2460 K. Modelling results show that the evolution of the explosion flame shape experiences four typical stages, ie spherical flame, finger-shape flame, flame with the skirt touching the side walls (ribs) and tulip flame, which are similar to the pattern of a duct explosion. The pressure in the gateroad remains the same as the initial value before the arrival of the explosion wave and then increases rapidly to the maximum value. Modelling results from this study will be used for the design of explosion arresting devices and mine seals in underground coalmines.CITATION:Liu, A and Ren, T, 2017. Computational simulation of gas explosion and its propagation in single entry gateroad, in Proceedings Australian Mine Vent Conference 2017, pp 181–188 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By Hongfa Hu, Stavros A. Argyropoulos

"This paper describes a mathematical model which simulates numerically reaction driven fluid flow phenomena. The driving force of this reaction is an exothermic heat of mixing. In addition, the model predicts the heat and mass transfer phenomena where both heat source and heat sink co-exist in close proximity. The heat source is generated by an exothermic reaction. The heat sink is formed by a moving boundary such as the melting of a solid. This type of phenomena occur quite often in various metal processing operations in which exothermic additions are immersed in liquid metals. The model is based on the SIMPLER algorithm and uses an enthalpy method to predict the fluid flow, temperature, and concentration fields. The results indicate that the exothermic mixing reaction was responsible for an abrupt rise in temperature around the moving boundary. The intensity of this reaction was also found to be responsible for the enhanced convection of fluid and the acceleration of the moving boundary. The modelling results were also verified by experimental work which included velocity and temperature measurements in a low temperature physical model. IntroductionAlloying additions are used extensively in the treatment of liquid metals during metallurgical processes. The alloying additions introduced into liquid metals can be classified into various classes, each of which follows its own route[l]. As a major group, the exothermic additions follow two different steps during their assimilation into liquid metals. In the first step, upon immersion, a metal shell solidifies around such additions, and then melts back. At this point, the second step commences. During this second step, due to the mixing of the addition with a liquid metal, an exothermic reaction occurs, which liberates large amounts of heat, resulting in an enhanced convection in the liquid metal surrounding the addition."

Jan 1, 1994

By F. Michael Hosking

Modeling of a furnace brazing process is described. The computational tools predict the thermal response of loaded hardware in a hydrogen brazing furnace to programmed furnace profiles. Experiments were conducted to validate the model and resolve computational uncertainties. The results from selected furnace simulations and measured thermal events were compared. Critical boundary conditions that affect materials and processing response to the furnace environment were determined. "Global" and local issues (i.e., at the furnace/hardware and joint levels, respectively) are discussed. The ability to accurately simulate and control furnace conditions is examined.

Jan 1, 1998

By A. J. Paul, K. O. Yu

"Today, foundries are moving towards the use of models and design tools to gain a competitive advantage in producing castings of high desired quality. This leads to a growing alliance between foundries, software developers and researchers seeking to model, visualize and understand the phenomena taking place during the casting process. In addition, there is a need to develop affordable techniques to produce parts in small lot sizes. This leads to the development of a Flexible Manufacturing System consisting of: (1) up-front computer-aided engineering; (2) computer integrated proto typing with solid freeform fabrication; and (3) fabrication of the actual mold and related equipment to cast the part.This paper discusses some of the developments that are taking place today in the areas of modeling the physical phenomena during the casting process as well as towards developing a Flexible Manufacturing System for producing cast parts. Areas that require most work involve prediction of defects and mechanical properties using simplified analyses. In addition, electronic data sharing for collaborative engineering between geographically dispersed team members is also discussed. Case studies are presented showing successes as well as failures.IntroductionCasting, one of the oldest forms of metalworking, has recently seen a flurry of developments in the area of solidification modeling. These developments have come about after the realization that, in order to stay competitive, foundries need to reduce their scrap rate and production costs, and increase casting quality. Even though this is not new knowledge for foundry engineers, the tools to help them achieve this goal are just being developed and put in place for use by foundries. Several state-of-the-art software packages are currently available to analyze the solidification behavior in complex shaped castings. These packages make use of several different approaches for solving the various problems associated with casting processes. The overall architecture of a comprehensive solidification modeling system is shown in Figure 1."

Jan 1, 1994

By C. D. Seybert, J. W. Evans

"The elimination of convection is essential in experimental investigations of diffusive transport (of heat and matter) during solidification. This paper describes an investigation of an approach whereby a magnetic field gradient is applied to a electrically non-conducting diamagnetic liquid. A magnetic body force then arises which is dependent on the volume susceptibility of the liquid and thereby on the density. With the field gradient aligned vertically and of correct magnitude, the variation of gravitational body forces due to density variations (arising from temperature variations, for example) can be counterbalanced by a variation in magnetic body force.Preparatory to a study of convection control in diamagnetic liquids, PN measurements have been made of the convection occurring during the solidification of water. A peculiar flow arises because of the density maximum at 4°C. Modeling of the flow the steady-state solidification of water in an extremely high field magnet at the NHMFL indicates that flow can be significantly reduced, but it is suggested that, due to field gradient variations within the cell, flow cannot be completely halted. INTRODUCTIONNatural convection is inherently a part of terrestrial solidification. Density-based convection during solidification, due to gradients of temperature and/or concentration, has a significant effect on a material's properties. The design of products with specific material characteristics has required the development of many processes to control convection (such as in the growth of semiconductor crystals, and electromagnetic stirring in steel casting). The expansion of fundamental knowledge about the process of solidification requires collecting data in the absence of density-based convection, while most of science's solidification data (and thus the equations that science has fitted to those data) have been obtained under the influence of gravity. Only relatively recently, through clever experimental design (e.g., drop towers, high altitude parabolic flights, and space laboratories), have investigators been able to study solidification in an environment with ""micro-gravity""."

Jan 1, 2001

By Jie E. Zhou, Yu U. Wang

"Development of crystallographic texture in polycrystals during templated grain growth process is studied by phase field modeling and computer simulation. To characterize the grain texture development, X-ray diffraction peak intensities are computed for the evolving grain structures as simulated by the phase field model, based on which Lotgering factor is further calculated as a quantitative measurement of uniaxial texturing. While the phase field modeling allows direct comparison between simulated grain structures and experimental microscopy observations, the computational diffraction allows convenient correlation between computer simulation and experimental X-ray diffraction characterization. The latter feature is especially desirable, since microscopy experiments normally require more efforts than X-ray diffraction, and diffraction is usually the preferred choice for material characterization.IntroductionThe properties of individual grains in polycrystals are generally anisotropic, while untextured polycrystalline materials with random grain orientations exhibit isotropic macroscopic properties that are independent of directions. In order to achieve anisotropic response in polycrystals, crystallographic texturing of grains is required [1]. Texture refers to the collective distribution of grain orientations towards preferred orientation in a polycrystal. To develop texture, special processing routes are needed, such as templated grain growth (TGG) for uniaxial texture [2]. TGG has been shown to provide uniaxial texture in wide variety of materials. For example, [001]-textured ferroelectric polycrystalline ceramics have been fabricated by TGG process, which exhibit enhanced piezoelectric properties [3]. Such highly textured polycrystalline materials offer better cost-performance ratio than single crystals. Thus, texture development in polycrystals is of technological importance for material applications.In this computational work, grain texture development in polycrystals during TGG process is studied. Grain structure evolution is simulated by phase field model, X-ray diffraction peak intensities for the evolving grain structures are computed, and Lotgering factor is calculated to quantitatively measure the development of uniaxial texturing. The phase field modeling allows direct comparison between simulated grain structures and experimental microscopy observations using imaging techniques such as scanning electron microscopy or optical microscopy. The computational diffraction allows convenient correlation between computer simulation and experimental X-ray diffraction characterization. The latter feature is especially desirable, because microscopy experiments normally require more efforts than X-ray diffraction, thus diffraction is usually the preferred choice for material characterization."

Jan 1, 2014

By S. K. Lahiri, K. C. Ghanta

Design of industrial slurry pipelines is usually performed by applying semi-empirical procedures, requiring a significant experimental study for each project. The mechanisms of suspension flow are not yet completely understood and existing predictive models cover only some aspects of uniform or closely graded particle slurry flows. This paper presents a computational technique for prediction of the velocity and concentration profile in slurry pipelines based on computational fluid dynamics. This model gives numerical solutions for the concentration and velocity distributions in the pipeline cross-section. The model prediction and experimental concentration and velocity profiles were found to be in good agreement. Keywords: pressure drop; concentration profile; particle diffusivity; slurry flow.

Jan 1, 2007

By Günter Petzow, Hans Leo Lukas, Hans Jürgen Seifert

"The CALPHAD method (CALculation of PHAse Diagrams) has been extensively developed in the last 25 years and became a useful tool in materials science. Thermodynamic descriptions for the functions of state of unary, binary and ternary phases are derived by the optimization of phase diagrams. These functions are stored in computerized thermochemical databases and can be combined to extrapolate to multi component systems. Depending on special demand, the actually most advantagous presentations of the calculated results can be chosen: tables or in a clear graphical form as phase diagrams, phase amount diagrams or volatility diagrams. The method will be desribed by the system Ti-Si-C-N-O including the ceramic subsystem Si3N4-SiC-TiCi,N1_1,-C-N-O which is very important for the development of ceramic composites. The calculations give the thermodynamic stabilities of the condensed phases as function of temperature, concentration and partial pressure of different gas species. Adjusting the sintering conditions to these results the formation of unfavourable compounds or liquid phases can be suppressed.IntroductionThe CALculation of PHAse Diagrams (CALPHAD-method) of multicomponent systems provides the possibility to plan experiments very efficiently and avoid the experimental trial and error approach for the development of materials. The main problem for best use of calculated results is their interpretation with regard to the specific applications under consideration. Tables give the exact quantitative data for the treated phenomena. However, most important to make best use of these thermodynamic data is their graphical representation especially designed for the solution of specific problems, scientific as well as application oriented. Only well chosen graphical representations support a comprehensive understanding of the thermodynamic interrelationships and the transfer to the problem."

Jan 1, 1996

By Judy Che, Steven Ceccio, Gretar Tryggvason

"A detailed understanding of drop deformation and solidification is essential for quantitative predictions of geometry and properties of parts made by ballistic particle manufacturing processes. Axisymmetric results of towers built by the deposition of multiple drops are presented. In these computations, fluid flow, heat transfer, and phase change are fully coupled throughout the drop deformation and solidification process. The solution method is based on a single set of conservation equations written for all phases simultaneously. The phase boundaries are treated as imbedded interfaces by adding the appropriate source terms to the conservation equations. A parameter study demonstrates the effect of Weber number, Peclet number, and drop deposition frequency on the final shape of the structure. Numerical results show that most successful method of building uniform towers is when two conditions are met. First, each drop solidifies at the same time in the deformation cycle. Second, the cooling rate is slow enough to allow for good adhesion between drops. The ability to predict the final shape of deposited drops will greatly reduce the amount of experimentation necessary to select the desired set parameters for any artifact.IntroductionMaterial deposition techniques based on layering small molten metal drops holds the promise to build small, coherent three-dimensional structures. In this process, numerous 20-100 µm diameter drops are deposited onto a substrate with a low impact velocity (on the order of 5 mis). Both the momentum and trajectory of each drop are controlled precisely to build up complex parts. This material layering technique differs from processes such as spray forming and splat quenching which involve high impact velocities (on the order of 100 mis) and high frequency deposition with little control over individual drop placement. This process of layering small drops can produce parts with near net shape accuracy, while spray forming produces slabs of material which must then be worked to make a usable part. The ability to computationally predict final drop shape and cooling rate has the advantage of allowing the user to select parameters to produce parts with desired shape and mechanical properties. However, the development of such predictive methods requires a thorough understanding of both drop deformation and solidification"

Jan 1, 1999

By H. W. Smith, N. Ichiyen

A convenient method for the calculation of metallurgical balances, based on statistical treatment of all available data, is presented. An error analysis is included. Examples show the advantages of the method, and also that such balances are less precise than might be supposed.

Jan 1, 1973

By Dave Proudfoot, Mike van Wyk

"There has akvays been plenty of discussion around the ‘accuracy of pyrotechnic detonators withmost recognised manufacturers claiming a variability of arourid 1% or less for their ‘superaccurate’ pyrotechnic based detonators. It is only now being understood that this 1% variabilitycan have serious adverse effects on blast performance. For example a 1% accurate 500millisecond shock tube detonator can fire anywhere between 485ms and 515ms. When wecouple these rather inaccurate ‘accurate’ detonators with short delays on surface, such as a 17millisecond connector, the probability of delay crowding and even out of sequence firing is quitehigh."

Jan 1, 1998

The geologists at the Zinc Mine in Broken Hill have developed a method of logging core using portable MS-DOS computers and LOTUS 123. The computer based logging system has almost halved both the time and cost to produce a completed log. The system is fast, flexible, easy and pleasant to use.

Jan 1, 1990

By I. E. Lane

Conventional demand management techniques invariably fail to offer optimum control flexibility in an operationally complex gold mining environment. An improved control system for electrical demand management is proposed. The system is designed to provide more effective load scheduling and control strategies by means of a computer aided demand management system (CADMS). The objective of the CADMS is to provide a responsive computational aid and adaptive control system for effective demand management. The system consists of a short term load forecasting module, an interactive load scheduling module, an incentive based electricity cost allocation module and a power management information module.

Jan 1, 1987

By Milawarma E, Cusack C

The Sapan Dalam coal deposit of Indonesia consists of ten steeply dipping seams with thicknesses varying between 0.1 and 3.5 m and split by shale, clay, silt and sandstone. The area contains four faults dipping about 75¦ with four to 85 m vertical displacements. The complex nature of the deposit coupled with limited 27 exploration drillholes at an average spacing of 200 m made it difficult to create a realistic geological model. A three-dimensional gridded seam model gave a fair representation of the deposit. Attempt to create an optimum pit using the WHITTLE 3D pit optimiser proved unsuccessful since the pit optimiser is restricted to standard regular or fixed blocks. The gridded seam model was converted to a fixed block model prior to the optimum pit design. Smoothing and pit base controlling were also introduced to obtain a smoother pit. A mining scenario produced 3.6 million tonnes of coal, 28.4 million bcm of waste and US$18.1 million revenue.

Jan 1, 1995

By N. El-Kaddah, J. W. McKelliget

"A mathematical model for the analysis and design of hybrid plasma reactors for advanced materials synthesis is presented. The model is based upon a solution of the electromagnetic vector potential equation and is capable of predicting the two-dimensional velocity, temperature, and electromagnetic fields as well as the reaction kinetics inside the reactor for any axi-symmetric coil configuration. The model is used as a computer aided design tool for the design of hybrid plasma reactors consisting of a conventional DC torch augmented by an RF induction coil and it is demonstrated that the hybrid system possesses superior characteristics for materials synthesis over conventional DC or RF systems. The coupling between the RF and DC components is found to affect both the temperature field and the flow field and to have a significant effect on the reaction kinetics and on materials recovery. The model is used to study the thermal decomposition of silicon tetrachloride as a function of reactor design and operating parameters and it is demonstrated that through a CAD approach it is possible to significantly improve the operation of materials synthesis systems.IntroductionIn recent years there has been growing interest in the use of the inductively coupled plasma for chemical synthesis as a way of meeting the increasing demand for high quality, high performance materials for use in critical applications/l/. Although the basic feasibility of this approach has been demonstrated in the laboratory/2,3/ there still exists a number of operational problems that adversely affect system performance for some applications. In particular, the recirculation and back flow effects that arise from the electromagnetic forces in the plasma can result in the repulsion of the reactants from the hot plasma core and their subsequent deposition on the walls of the reactor. Another operational problem arises from the fact that the energy dissipated in the plasma has to compensate for the heat losses to the environment by conduction, convection, and radiation in order to maintain the ionization of the plasma and, hence, the stability of the plasma may be affected by the presence of the reactants and their products."

Jan 1, 1988