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Brachypodium distachyon, is a new model plant for most cereal crops while gliadin is a class of wheat storage proteins related with wheat quality attributes. In the published B. distachyon genome sequence databases, no gliadin gene is found. In the current study, a number of gliadin genes in B. distachyon were isolated, which is contradictory to the results of genome sequencing projects. In our study, the B. distachyon seeds were found to have no gliadin protein expression by gel electrophoresis, reversed-phase high-performance liquid chromatography and Western blotting analysis. However, Southern blotting revealed a presence of more than ten copies of α-gliadin coding genes in B. distachyon. By means of AS-PCR amplification, four novel full-ORF α-gliadin genes, and 26 pseudogenes with at least one stop codon as well as their promoter regions were cloned and sequenced from different Brachypodium accessions. Sequence analysis revealed a few of single-nucleotide polymorphisms among these genes. Most pseudogenes were resulted from a C to T change, leading to the generation of TAG or TAA in-frame stop codon. To compare both the full-ORFs and the pseudogenes among Triticum and Triticum-related species, their structural characteristics were analyzed. Based on the four T cell stimulatory toxic epitopes and two ployglutamine domains, Aegilops, Triticum, and Brachypodium species were found to be more closely related. The phylogenetic analysis further revealed that B. distachyon was more closely related to Aegilops tauschii, Aegilops umbellulata, and the A or D genome of Triticum aestivum. The α-gliadin genes were able to express successfully in E. coli using the functional T7 promoter. The relative and absolute quantification of the transcripts of α-gliadin genes in wheat was much higher than that in B. distachyon. The abundant pseudogenes may affect the transcriptional and/or posttranscriptional level of the α-gliadin in B. distachyon.

An efficient N-heterocyclic carbene (NHC)-catalyzed internal redox reaction of alkynals that bear a γ leaving group has been developed. This process provides a new access to a range of allenoates in good yields. Preliminary results demonstrate that the enantioselective variant can also be achieved. © 2012 American Chemical Society.

We have observed the bulk Fermi surface (FS) in an overdoped (x=0.3) single crystal of La2?xSrxCuO4 by using Compton scattering. A two-dimensional (2D) momentum density reconstruction from measured Compton profiles yields a clear FS signature in the third Brillouin zone along [100]. The quantitative agreement between density functional theory (DFT) calculations and momentum density experiment suggests that Fermi-liquid physics is restored in the overdoped regime. In particular the predicted FS topology is found to be in good accord with the corresponding experimental data. We find similar quantitative agreement between the measured 2D angular correlation of positron annihilation radiation (2D-ACAR) spectra and the DFT-based computations. However, 2D-ACAR does not give such a clear signature of the FS in the extended momentum space in either the theory or the experiment., RRR/Radiation, Radionuclides and Reactors, Applied Sciences

We present an approximation for efficient calculation of the Lindhard susceptibility ?L(q,?) in a periodic system through the use of simple products of real space functions and the fast Fourier transform (FFT). The method is illustrated by providing ?L(q,?) results for the electron doped cuprate Nd2?xCexCuO4 extended over several Brillouin zones. These results are relevant for interpreting inelastic x-ray scattering spectra from cuprates., RRR/Radiation, Radionuclides and Reactors, Applied Sciences

We have observed the bulk Fermi surface (FS) in an overdoped (x=0.3) single crystal of La2?xSrxCuO4 by using Compton scattering. A two-dimensional (2D) momentum density reconstruction from measured Compton profiles yields a clear FS signature in the third Brillouin zone along [100]. The quantitative agreement between density functional theory (DFT) calculations and momentum density experiment suggests that Fermi-liquid physics is restored in the overdoped regime. In particular the predicted FS topology is found to be in good accord with the corresponding experimental data. We find similar quantitative agreement between the measured 2D angular correlation of positron annihilation radiation (2D-ACAR) spectra and the DFT-based computations. However, 2D-ACAR does not give such a clear signature of the FS in the extended momentum space in either the theory or the experiment., RRR/Radiation, Radionuclides and Reactors, Applied Sciences

We present an approximation for efficient calculation of the Lindhard susceptibility ?L(q,?) in a periodic system through the use of simple products of real space functions and the fast Fourier transform (FFT). The method is illustrated by providing ?L(q,?) results for the electron doped cuprate Nd2?xCexCuO4 extended over several Brillouin zones. These results are relevant for interpreting inelastic x-ray scattering spectra from cuprates., RRR/Radiation, Radionuclides and Reactors, Applied Sciences

This Brief Report presents giant extraordinary Hall effect (EHE) in the Ru-mediated antiferromagnetically coupled [Pt/Co]5/Ru/[Co/Pt]5 multilayers (MLs) compared with those MLs without the Ru spacer. The enhancement of the EHE is attributed to the strong Ru/Co interface scattering. Through the variation in the Pt layer thickness and the temperature, we determine the relation between the Hall voltage and the longitudinal resistivity. It is found that the conventional scaling analysis has difficulties in consistently interpreting our data.

This Brief Report presents giant extraordinary Hall effect (EHE) in the Ru-mediated antiferromagnetically coupled [Pt/Co]5/Ru/[Co/Pt]5 multilayers (MLs) compared with those MLs without the Ru spacer. The enhancement of the EHE is attributed to the strong Ru/Co interface scattering. Through the variation in the Pt layer thickness and the temperature, we determine the relation between the Hall voltage and the longitudinal resistivity. It is found that the conventional scaling analysis has difficulties in consistently interpreting our data.

We have carried out first-principles calculations of the Compton scattering spectra to demonstrate that the filling of the hole Fermi surface in LaO1?xFxFeAs produces a distinct signature in the Fourier-transformed Compton spectrum when the momentum transfer vector lies along the [100] direction. We thus show how the critical concentration xc, where hole Fermi-surface pieces are filled up and the superconductivity mediated by antiferromagnetic spin fluctuations is expected to be suppressed, can be obtained in a bulk-sensitive manner., Radiation, Radionuclides and Reactors, Applied Sciences

This Brief Report presents giant extraordinary Hall effect (EHE) in the Ru-mediated antiferromagnetically coupled [Pt/Co]5/Ru/[Co/Pt]5 multilayers (MLs) compared with those MLs without the Ru spacer. The enhancement of the EHE is attributed to the strong Ru/Co interface scattering. Through the variation in the Pt layer thickness and the temperature, we determine the relation between the Hall voltage and the longitudinal resistivity. It is found that the conventional scaling analysis has difficulties in consistently interpreting our data.

This Brief Report presents giant extraordinary Hall effect (EHE) in the Ru-mediated antiferromagnetically coupled [Pt/Co]5/Ru/[Co/Pt]5 multilayers (MLs) compared with those MLs without the Ru spacer. The enhancement of the EHE is attributed to the strong Ru/Co interface scattering. Through the variation in the Pt layer thickness and the temperature, we determine the relation between the Hall voltage and the longitudinal resistivity. It is found that the conventional scaling analysis has difficulties in consistently interpreting our data.

We have carried out first-principles calculations of the Compton scattering spectra to demonstrate that the filling of the hole Fermi surface in LaO1?xFxFeAs produces a distinct signature in the Fourier-transformed Compton spectrum when the momentum transfer vector lies along the [100] direction. We thus show how the critical concentration xc, where hole Fermi-surface pieces are filled up and the superconductivity mediated by antiferromagnetic spin fluctuations is expected to be suppressed, can be obtained in a bulk-sensitive manner., Radiation, Radionuclides and Reactors, Applied Sciences

< 110 > oriented nanotrenches were generated by thermally annealing an ultrathin An layer deposited on ZnSe surfaces of different orientations. Results from a number of structural and chemical analyses indicate that they were induced by the migration of Au-alloy droplets through a catalytic reaction with ZnSe. Highly aligned nanotrenches can be achieved on (100)-oriented substrates, which can potentially serve as templates for the fabrication of one-dimensional nanostructures of various materials. 0 2008 American Institute of Physics.

< 110 > oriented nanotrenches were generated by thermally annealing an ultrathin An layer deposited on ZnSe surfaces of different orientations. Results from a number of structural and chemical analyses indicate that they were induced by the migration of Au-alloy droplets through a catalytic reaction with ZnSe. Highly aligned nanotrenches can be achieved on (100)-oriented substrates, which can potentially serve as templates for the fabrication of one-dimensional nanostructures of various materials. 0 2008 American Institute of Physics.

< 110 > oriented nanotrenches were generated by thermally annealing an ultrathin An layer deposited on ZnSe surfaces of different orientations. Results from a number of structural and chemical analyses indicate that they were induced by the migration of Au-alloy droplets through a catalytic reaction with ZnSe. Highly aligned nanotrenches can be achieved on (100)-oriented substrates, which can potentially serve as templates for the fabrication of one-dimensional nanostructures of various materials. 0 2008 American Institute of Physics.

A predictive, physically based substrate resistance model for CMOS transistors operating at radio frequencies (RF) is described. This analytical mod el is scalable with transistor size and layout geometry. Measurement results confirm that the model accurately predicts the effect of substrate resistance on the transistor output impedance up to 20 GHz, including gate and drain bias dependencies. Minimization of the substrate resistance can be achieved by using substrate tap rings with small spacer distances and short finger widths.

A predictive, physically based substrate resistance model for CMOS transistors operating at radio frequencies (RF) is described. This analytical mod el is scalable with transistor size and layout geometry. Measurement results confirm that the model accurately predicts the effect of substrate resistance on the transistor output impedance up to 20 GHz, including gate and drain bias dependencies. Minimization of the substrate resistance can be achieved by using substrate tap rings with small spacer distances and short finger widths.

A predictive, physically based substrate resistance model for CMOS transistors operating at radio frequencies (RF) is described. This analytical mod el is scalable with transistor size and layout geometry. Measurement results confirm that the model accurately predicts the effect of substrate resistance on the transistor output impedance up to 20 GHz, including gate and drain bias dependencies. Minimization of the substrate resistance can be achieved by using substrate tap rings with small spacer distances and short finger widths.

An integrated engineering design approach to mine ventilation and air conditioning is presented with the aim of advancing an understanding of comprehensive environmental control of the mine atmosphere. Total mine air conditioning is advocated through simultaneous control of the quality, quantity and temperature-humidity of the underground environment. Chapters are included on properties and behaviour of air, mine gases, dusts and other mine aerosols, air flow through mine openings and ducts, ventilation measurements and surveys, mine ventilation circuits and networks, natural ventilation, air-moving equipment, fans, auxiliary ventilation and controlled recirculation, economics of air flow, coal mine ventilation systems, metal mine ventilation systems, control of mine fires and explosions, heat sources and effects in mines and mine air conditioning systems. Appendices include reference tables and figures, laboratory experiments and computer applications and software. There are 23 pages of references and a subject index., An integrated engineering design approach to mine ventilation and air conditioning is presented with the aim of advancing an understanding of comprehensive environmental control of the mine atmosphere. Total mine air conditioning is advocated through simultaneous control of the quality, quantity and temperature-humidity of the underground environment. Chapters are included on properties and behaviour of air, mine gases, dusts and other mine aerosols, air flow through mine openings and ducts, ventilation measurements and surveys, mine ventilation circuits and networks, natural ventilation, air-moving equipment, fans, auxiliary ventilation and controlled recirculation, economics of air flow, coal mine ventilation systems, metal mine ventilation systems, control of mine fires and explosions, heat sources and effects in mines and mine air conditioning systems. Appendices include reference tables and figures, laboratory experiments and computer applications and software. There are 23 pages of references and a subject index.

We report the temperature dependence of the effective perpendicular anisotropy and interface anisotropy in the temperature region of 80K to 290K for Co/Pt and Co/Au multilayers. Different temperature dependence of the interface anisotropy have been observed for these two types of multilayers. We speculate that the strain due to the lattice misfit may not be the main reason responsible for the perpendicular anisotropy in Co/Pt and Co/Au multilayers.

After a keynote address on 50 years of progression in ventilation, the papers are presented under the following 11 headings: Mine fires, spontaneous combustion and emergencies (13 papers); Mine gases and outbursts (11 papers); Mine dusts (8 papers); Mine environment and diesel emissions (9 papers); Mine ventilation system and network analysis I (8 papers); Mine ventilation system and network analysis II (5 papers); Mine ventilation fundamentals and instrumentation (8 papers); Mine ventilation monitoring and control (5 papers); Expert system and computer applications (6 papers); Case studies (4 papers); and Special topics (7 papers)., After a keynote address on 50 years of progression in ventilation, the papers are presented under the following 11 headings: Mine fires, spontaneous combustion and emergencies (13 papers); Mine gases and outbursts (11 papers); Mine dusts (8 papers); Mine environment and diesel emissions (9 papers); Mine ventilation system and network analysis I (8 papers); Mine ventilation system and network analysis II (5 papers); Mine ventilation fundamentals and instrumentation (8 papers); Mine ventilation monitoring and control (5 papers); Expert system and computer applications (6 papers); Case studies (4 papers); and Special topics (7 papers).

The papers are presented in eight sessions: Mine automation, which includes papers on real-time control systems, neural network navigation and utilisation of mechanical linear transducers; Application of geostatistical methods in coal preparation and quality control I (2 papers); Ground control I, which includes papers on using CISPM in subsidence research and control, using AutoCAD to monitor abandoned mine land subsidence, applied geotechnical monitoring and application of MULSIM/PC in a coal mine structural analysis; Mine ventilation, which includes papers on the application of graph theory to detect uncontrolled recirculation and selection of miner escape paths; Mine management, which includes papers on computer-based integrated mine management systems, manpower planning and a transportation and sales MIS system; Ground control II, which includes papers on predicting rock falls using discriminant analysis and geostatistics, the application of microcomputers in the systematic design of powered supports, and cost-based optimisation for roof control; Mine-plant planning and design, which includes papers on a CAD approach to mine planning and production scheduling, computer-aided evaluation of reserves and PERT analysis for the determination of optimum cycle paths in opencast mines; Information systems, which includes papers on the use of the OSM technical information processing system for three-dimensional analysis of overburden quality, storage and retrieval system of coal mine maps and design and application of the MIS system for geology and surveying; and Application of geostatistical methods in coal preparation and quality control II (3 papers)., The papers are presented in eight sessions: Mine automation, which includes papers on real-time control systems, neural network navigation and utilisation of mechanical linear transducers; Application of geostatistical methods in coal preparation and quality control I (2 papers); Ground control I, which includes papers on using CISPM in subsidence research and control, using AutoCAD to monitor abandoned mine land subsidence, applied geotechnical monitoring and application of MULSIM/PC in a coal mine structural analysis; Mine ventilation, which includes papers on the application of graph theory to detect uncontrolled recirculation and selection of miner escape paths; Mine management, which includes papers on computer-based integrated mine management systems, manpower planning and a transportation and sales MIS system; Ground control II, which includes papers on predicting rock falls using discriminant analysis and geostatistics, the application of microcomputers in the systematic design of powered supports, and cost-based optimisation for roof control; Mine-plant planning and design, which includes papers on a CAD approach to mine planning and production scheduling, computer-aided evaluation of reserves and PERT analysis for the determination of optimum cycle paths in opencast mines; Information systems, which includes papers on the use of the OSM technical information processing system for three-dimensional analysis of overburden quality, storage and retrieval system of coal mine maps and design and application of the MIS system for geology and surveying; and Application of geostatistical methods in coal preparation and quality control II (3 papers).

Systematic studies of rare-earth–transition-metal amorphous compositionally modulated films (CMF) permit the development of a detailed model for understanding the magnetization and perpendicular magnetic anisotropy and their distributions along the film normal. It is shown that the single-ion anisotropy of rare-earth ions with orbital angular momentum is the major contributor to the perpendicular anisotropy for this class of CMF. The calculated results agree well with the experimental data for Dy/Co and Tb/Fe CMF when the individual layer thicknesses are small enough (<10 Å); these films have structures which can be characterized as compositionally modulated amorphous alloys.

The work is intended as a textbook which covers ventilation including new techniques: namely the role of computers in modelling and mine ventilation. It covers the cooling systems and the airflow measurements. Legislation and economics are discussed., The work is intended as a textbook which covers ventilation including new techniques: namely the role of computers in modelling and mine ventilation. It covers the cooling systems and the airflow measurements. Legislation and economics are discussed.

The primary advantages of using the methods outlined are as follows: CPM is a readily-available software package that is convenient to use for computer-aided mine ventilation network analysis; network analysis procedures using cutset operations provide the basis for optimising power consumption in mine ventilation networks; the analysis of regulator relocation using cutset operations permits the ventilation planner a maximum of freedom without increasing power costs; and the number of devices to introduce artificial head in the network can be minimised., The primary advantages of using the methods outlined are as follows: CPM is a readily-available software package that is convenient to use for computer-aided mine ventilation network analysis; network analysis procedures using cutset operations provide the basis for optimising power consumption in mine ventilation networks; the analysis of regulator relocation using cutset operations permits the ventilation planner a maximum of freedom without increasing power costs; and the number of devices to introduce artificial head in the network can be minimised.

Includes 78 papers, in sections on: mining systems; coal preparation; data acquisition and data base management; manpower and training; reserve analysis and cost models; computer systems selection and installation; ground control; health and safety; mine ventilation and fire; special applications., Includes 78 papers, in sections on: mining systems; coal preparation; data acquisition and data base management; manpower and training; reserve analysis and cost models; computer systems selection and installation; ground control; health and safety; mine ventilation and fire; special applications.

It is concluded that the oxides of elements such as K, Na and Zn are reduced by CO in the lower part of the furnace and oxidised by CO2 in the upper part, decreasing gas utilisation and increasing heat consumption. The effects of different element accumulation times on the coke ratio are in decreasing order Na, K, Zn whereas the effects of their loads decrease from Zn through Na to K. The increase in heat consumption has more effect on the coke ratio than the decrease in gas utilisation., It is concluded that the oxides of elements such as K, Na and Zn are reduced by CO in the lower part of the furnace and oxidised by CO2 in the upper part, decreasing gas utilisation and increasing heat consumption. The effects of different element accumulation times on the coke ratio are in decreasing order Na, K, Zn whereas the effects of their loads decrease from Zn through Na to K. The increase in heat consumption has more effect on the coke ratio than the decrease in gas utilisation.

The operating points are represented as the intersection of the modified fan curves. In constructing the diagram, the air quantities associated with the fans are considered to be independent variables and are employed as the axes of a rectangular coordinate system. In addition to the modified fan curves, the diagram may include, contour lines for resistances, pressures, and air powers. Procedures for drawing the diagram are discussed and illustrated with an example of the ventilation system., The operating points are represented as the intersection of the modified fan curves. In constructing the diagram, the air quantities associated with the fans are considered to be independent variables and are employed as the axes of a rectangular coordinate system. In addition to the modified fan curves, the diagram may include, contour lines for resistances, pressures, and air powers. Procedures for drawing the diagram are discussed and illustrated with an example of the ventilation system.

To establish a major simplification in the development of procedures for determining the operating point for a mine/fan combination, it is suggested that mine pressures be redefined and then used in such a manner that conservation of energy is ensured. On this basis the recommendation that the fan operating point be determined using fan total pressure and system total pressure characteristics applies. A set of procedures is provided for determining the operating point of a mine/fan system where the outlet areas of the mine and fan are known. This procedure can be applied to fans in the blower, booster, and exhaust positions and to both single-fan and multiple-fan networks. The method is also applicable to fans with or without an evase., To establish a major simplification in the development of procedures for determining the operating point for a mine/fan combination, it is suggested that mine pressures be redefined and then used in such a manner that conservation of energy is ensured. On this basis the recommendation that the fan operating point be determined using fan total pressure and system total pressure characteristics applies. A set of procedures is provided for determining the operating point of a mine/fan system where the outlet areas of the mine and fan are known. This procedure can be applied to fans in the blower, booster, and exhaust positions and to both single-fan and multiple-fan networks. The method is also applicable to fans with or without an evase.

A method of designing a mine ventilation system to minimise cost components of a controlled-flow network is presented. Cost elements considered include the cost of power and the fixed cost of fans. A mixed-integer linear programming format is used in modelling and problems solved by the branch and bound method to yield the optimum configuration of fans. The use of booster fans has been shown to decrease air power required but increase initial cost of the system. The minimum system cost is achieved by selecting the optimal number and placement of fans in the system. An example network is used to illustrate the model., A method of designing a mine ventilation system to minimise cost components of a controlled-flow network is presented. Cost elements considered include the cost of power and the fixed cost of fans. A mixed-integer linear programming format is used in modelling and problems solved by the branch and bound method to yield the optimum configuration of fans. The use of booster fans has been shown to decrease air power required but increase initial cost of the system. The minimum system cost is achieved by selecting the optimal number and placement of fans in the system. An example network is used to illustrate the model.

The definitions of system pressure loss (mine head) and system resistance, which are traditionally associated with single-fan networks, are applied to multiple-fan ventilation networks. The system characteristics, relations between air power, pressure loss, air quantity and resistance, are analysed by introducing the concept of subsystems. The minimum system resistance provides a basis for comparing the different networks., The definitions of system pressure loss (mine head) and system resistance, which are traditionally associated with single-fan networks, are applied to multiple-fan ventilation networks. The system characteristics, relations between air power, pressure loss, air quantity and resistance, are analysed by introducing the concept of subsystems. The minimum system resistance provides a basis for comparing the different networks.

The effects of air leakage from intake to return airways, through a series of stoppings, on the analysis of coal mine ventilation is considered. The mathematical model which assumes continuous leakage along adjoining intake and return airways is reviewed, and a new mathematical approach is presented, based on the concentrated leakage through individual stoppings. The new method is used to illustrate the effects of leakage on the pressure loss and power consumption in coal mine ventilation networks., The effects of air leakage from intake to return airways, through a series of stoppings, on the analysis of coal mine ventilation is considered. The mathematical model which assumes continuous leakage along adjoining intake and return airways is reviewed, and a new mathematical approach is presented, based on the concentrated leakage through individual stoppings. The new method is used to illustrate the effects of leakage on the pressure loss and power consumption in coal mine ventilation networks.

This new method for solving ventilation networks with natural splitting shows that the problem can be formulated and analysed as an unconstrained optimisation (minimisation) problem. The computational experience with the method of conjugate gradients is also discussed. The applicability of the algorithm is demonstrated with an example network., This new method for solving ventilation networks with natural splitting shows that the problem can be formulated and analysed as an unconstrained optimisation (minimisation) problem. The computational experience with the method of conjugate gradients is also discussed. The applicability of the algorithm is demonstrated with an example network.

An analysis is presented for multiple-fan ventilation networks where the total air quantity and the resistances for all branches are given. It is shown that the condition of equal fan pressure holds for a set of fans associated whith a special class of cutsets when the total air power of the network is minimised. With this condition, the problem of minimising the total air power simplifies to the solution of the single-fan problem. The theoretical basis for cutset operations is presented and the conditions under which the total air power remains unchanged in the cutset operation are discussed. These conditions are useful in exploring the alternative solutions that have the same total air power and air quantities as the known network solution., An analysis is presented for multiple-fan ventilation networks where the total air quantity and the resistances for all branches are given. It is shown that the condition of equal fan pressure holds for a set of fans associated whith a special class of cutsets when the total air power of the network is minimised. With this condition, the problem of minimising the total air power simplifies to the solution of the single-fan problem. The theoretical basis for cutset operations is presented and the conditions under which the total air power remains unchanged in the cutset operation are discussed. These conditions are useful in exploring the alternative solutions that have the same total air power and air quantities as the known network solution.

The paper is concerned with the sizing of conventionally-sunk circular shafts with concrete or shotcrete linings. Costs of sinking shafts of three different depths were obtained through questionnaires to shaft contractors. The primary objective of the economic model presented is the balancing of detailed annual capital and operating costs to achieve the minimum overall cost of the shaft installation over its life. Included is a detailed analysis of the effects of varying power costs on optimal shaft size, a statistical analysis of current shaft costs and comments on the choice between shotcrete and concrete linings., The paper is concerned with the sizing of conventionally-sunk circular shafts with concrete or shotcrete linings. Costs of sinking shafts of three different depths were obtained through questionnaires to shaft contractors. The primary objective of the economic model presented is the balancing of detailed annual capital and operating costs to achieve the minimum overall cost of the shaft installation over its life. Included is a detailed analysis of the effects of varying power costs on optimal shaft size, a statistical analysis of current shaft costs and comments on the choice between shotcrete and concrete linings.

By identifying the analogy between the network for controlled flow and that for the critial path method, the critical path method can be applied to a mine ventilation network where regulators and fans are employed to control a pre-assigned airflow. The effect of booster fans on the total air power consumed can also be assessed. The concept of cut-set is introduced to the problem to help in the evaluation of alternative layouts., By identifying the analogy between the network for controlled flow and that for the critial path method, the critical path method can be applied to a mine ventilation network where regulators and fans are employed to control a pre-assigned airflow. The effect of booster fans on the total air power consumed can also be assessed. The concept of cut-set is introduced to the problem to help in the evaluation of alternative layouts.

The usual method used to determine the direction of flow which will occur in a connecting airway is to conduct a survey between the two existing nodes being connected by the new airway. It is then assumed that air flow will take place from the node with higher pressure to the node with lower pressure. This direction-of-flow problem has been examined using properties of the system characteristic curve for a two-terminal network. Some conditions that ensure that flow will take place from the higher-pressure node to the lower-pressure node are specified. It is concluded that the only requirement is that all characteristic curves of fans in the network should be strictly decreasing. Five numerical examples illustrate some important properties of the direction-of-flow problem., The usual method used to determine the direction of flow which will occur in a connecting airway is to conduct a survey between the two existing nodes being connected by the new airway. It is then assumed that air flow will take place from the node with higher pressure to the node with lower pressure. This direction-of-flow problem has been examined using properties of the system characteristic curve for a two-terminal network. Some conditions that ensure that flow will take place from the higher-pressure node to the lower-pressure node are specified. It is concluded that the only requirement is that all characteristic curves of fans in the network should be strictly decreasing. Five numerical examples illustrate some important properties of the direction-of-flow problem.

When multiple axial-flow fans serve a ventilation system, their mutual impacts on the stability of the ventilation system are not well understood. Results from laboratory experiments showed that, when a fan is working across its stall zone, some branches in the system may suffer abrupt and even drastic changes in air quantity and pressure. The quantity range of the fan that causes this change is called an unstable operating range. The corresponding quantity range of a branch is called a nonachievable quantity range of the branch, because any quantity within this range cannot be achieved without changing some parameters of the ventilation system. Results from tests on laboratory tubing networks are used to discuss these characteristics., When multiple axial-flow fans serve a ventilation system, their mutual impacts on the stability of the ventilation system are not well understood. Results from laboratory experiments showed that, when a fan is working across its stall zone, some branches in the system may suffer abrupt and even drastic changes in air quantity and pressure. The quantity range of the fan that causes this change is called an unstable operating range. The corresponding quantity range of a branch is called a nonachievable quantity range of the branch, because any quantity within this range cannot be achieved without changing some parameters of the ventilation system. Results from tests on laboratory tubing networks are used to discuss these characteristics.

Formulae are presented for exact solution of air flows where branch resistances and external air flows are given. To derive the formulae, an equation representing pressure loss along any mesh or loop is written in terms of the air flow of a single branch. A quadratic equation is then constructed, one of whose solutions or roots agrees with the solution of the pressure-loss equation. The major computational task of the solution is determining the coefficients of the quadratic equation and finding one of its solutions by the quadratic formula. The application of the formulae is illustrated with two problems for quadrilateral networks., Formulae are presented for exact solution of air flows where branch resistances and external air flows are given. To derive the formulae, an equation representing pressure loss along any mesh or loop is written in terms of the air flow of a single branch. A quadratic equation is then constructed, one of whose solutions or roots agrees with the solution of the pressure-loss equation. The major computational task of the solution is determining the coefficients of the quadratic equation and finding one of its solutions by the quadratic formula. The application of the formulae is illustrated with two problems for quadrilateral networks.

The Hardy Cross method is the most popular technique for solving a ventilation network problem with natural air splitting. It solves each mesh equation by an approximation during each iteration. An algorithm is presented for computing the exact, rather than the approximate, solution to the mesh equation with a variable fan pressure. The algorithm uses signum functions for air quantities to generate an alternative mesh equation in the form of a quadratic equation, which has two solutions defined by the well-known quadratic formula. The condition that the derivatives of the alternative and the original equations must be the same provides a basis for the correct choice between the two solutions., The Hardy Cross method is the most popular technique for solving a ventilation network problem with natural air splitting. It solves each mesh equation by an approximation during each iteration. An algorithm is presented for computing the exact, rather than the approximate, solution to the mesh equation with a variable fan pressure. The algorithm uses signum functions for air quantities to generate an alternative mesh equation in the form of a quadratic equation, which has two solutions defined by the well-known quadratic formula. The condition that the derivatives of the alternative and the original equations must be the same provides a basis for the correct choice between the two solutions.

Discussion is presented of the graphical solutions to mine ventilation problems. Energy loss through friction and shock factors and energy input through mechanical devices can both be represented as positive values on the same axis, which has a great potential for confusion. By presenting all data for characteristic curves based on relative energy change and examining the result of combining curves into a single total system characteristic curve is just as accurate and is more intuitive. This method is applicable to all graphical techniques used for ventilation analysis., Discussion is presented of the graphical solutions to mine ventilation problems. Energy loss through friction and shock factors and energy input through mechanical devices can both be represented as positive values on the same axis, which has a great potential for confusion. By presenting all data for characteristic curves based on relative energy change and examining the result of combining curves into a single total system characteristic curve is just as accurate and is more intuitive. This method is applicable to all graphical techniques used for ventilation analysis.

A technique for modelling mine ventilation networks based on the analysis of electrical networks has been developed. Five basic elements are defined which characterise the branches of the ventilation network. These elements are defined by three variables, each of which may be known or unknown: pressure gain or loss, air quantity, and pressure-quantity relationship. The unique solutions to problems of defining ventilation values, derived using electrical network theory, might in some cases be obvious to the mine ventilation engineer, but in many cases useful insights can be gained., A technique for modelling mine ventilation networks based on the analysis of electrical networks has been developed. Five basic elements are defined which characterise the branches of the ventilation network. These elements are defined by three variables, each of which may be known or unknown: pressure gain or loss, air quantity, and pressure-quantity relationship. The unique solutions to problems of defining ventilation values, derived using electrical network theory, might in some cases be obvious to the mine ventilation engineer, but in many cases useful insights can be gained.

Just under 2 200 papers published in the Transactions were analysed, in 6 five-year periods, in terms of representation of topics, author information, computer usage, ore or product discussed and mining method discussed. In mining the most popular topic was rock mechanics and in beneficiation, mineral processing; the general or uncategorised area showed the largest growth and the largest subdiscipline within this category was environmental control. Three major implications from the study are: industry has reduced its research presence in the Transactions; not all mineral research activity is covered by the Transactions; and competing symposia are diluting the material available to Transactions., Just under 2 200 papers published in the Transactions were analysed, in 6 five-year periods, in terms of representation of topics, author information, computer usage, ore or product discussed and mining method discussed. In mining the most popular topic was rock mechanics and in beneficiation, mineral processing; the general or uncategorised area showed the largest growth and the largest subdiscipline within this category was environmental control. Three major implications from the study are: industry has reduced its research presence in the Transactions; not all mineral research activity is covered by the Transactions; and competing symposia are diluting the material available to Transactions.

This ventilation method has been applied to many mines since the 1930s but a generalised comprehensive network analysis is still lacking. A unique approach in which the network is divided into two subsystems is presented. The main subsystem and the recirculation subsystem are analysed individually and their pressure vs quantity curves that interact with the counterpart subsystem are constructed. The intersection of the characteristic curves represents the operating point of both subsystems. The required pressures for the booster fan and regulator in the recirculation subsystem can then be determined., This ventilation method has been applied to many mines since the 1930s but a generalised comprehensive network analysis is still lacking. A unique approach in which the network is divided into two subsystems is presented. The main subsystem and the recirculation subsystem are analysed individually and their pressure vs quantity curves that interact with the counterpart subsystem are constructed. The intersection of the characteristic curves represents the operating point of both subsystems. The required pressures for the booster fan and regulator in the recirculation subsystem can then be determined.