Continuous Emission Measurement Research Articles

A carbon calculator: the development of a user-friendly greenhouse gas measuring tool for general dental practice (Part 2).

The need to reduce carbon emissions and limit global warming to 1.5 °C has spurred various sectors towards net-zero emission goals. This paper introduces a specialised carbon calculator for dental practices to compute and monitor their carbon footprints (CFPs). The carbon calculator is developed using recent carbon modelling, utilising methodologies and data from estimating the average NHS dental practice's CFP. It employs both spend-based and activity-based carbon accounting methods, simplifying carbon emission estimation. It offers dental practices a user-friendly, rudimentary, cost-free tool to determine their baseline CFP and track sustainability progress. It includes conversion factors for patient travel, procurement and waste management, enabling practices to input data and generate personalised CFP charts. It also acknowledges assumptions and uncertainties related to procurement and waste management, emphasising the availability of personalised consultancy services for more precise carbon footprinting. This carbon calculator supports environmental sustainability in dental practices as an accessible starting point. By raising awareness of their CFP, it encourages progress in 'green dentistry' and promotes environmental responsibility in oral healthcare. The calculator is freely downloadable and part of a broader 'green dentistry' initiative. Continuous carbon emission measurement and monitoring are crucial for a sustainable future, with this tool aiding dental practitioners in their environmental contributions.

Deterioration Diagnosis Model for End Mill by Continuous Acoustic Emission Measurement

Deterioration Diagnosis Model for End Mill by Continuous Acoustic Emission Measurement

Deterioration Diagnosis Model for End Mill by Continuous Acoustic Emission Measurement

Deterioration Diagnosis Model for End Mill by Continuous Acoustic Emission Measurement

Laboratuvar Teknolojisi Programı Öğrencilerinin Teknik Gezi ile Çevre Analizleri Hakkında Farkındalıklarının Arttırılmasına Yönelik Çalışmanın Değerlendirilmesi

A technical trip was planned within the course of environmental analysis in the second-class curriculum and sampling methods in the first class curriculum of the Laboratory Technology Program. In this study, it was aimed to determine the effect of technical trip about awareness of our students about the parameters analysed in the environment. Students attended this technical trip stated in the survey conducted after the trip that their awareness increased about environmental analyses. They are continuous emission measurement systems, outdoor air quality measurements, air quality modelling, water analysis, water analysis modelling, occupational health and safety in field studies, occupational hygiene in field studies, environmental noise level examinations, the relationship of soil analysis with production and health and leaf analysis. The questionnaire was evaluated using the SPSS program and Cronbach Alpha reliability coefficient was calculated as 0.927.

Smokestack gas velocity measurements using 3D pitot tubes in a coal-fired power plant

On the path to carbon neutrality to reduce greenhouse gas (GHG) emissions, the Korean government has mandated legislation for controlling and monitoring GHG emissions emitted from smokestacks. A continuous emission measurement (CEM) method is considered to be the most reliable for determining CO2 emissions from stationary sources. In Korea, an S-type Pitot tube is the most popular technique to measure the gas velocity in a smokestack, but it will result in a certain error when the non-axial velocity components exist. To vanquish this limitation, Korea Research Institute of Standards and Science (KRISS) developed a nulling smokestack flow measurement (NSFM) instrument equipped with 3D Pitot tubes for taking on-site stack gas velocity measurements. 3D Pitot tubes used in this research, such as prism Pitot tube and sphere Pitot tube, are calibrated in the KRISS airspeed system. The instrument using 3D Pitot tubes with the nulling technique is expected to diminish the restriction on S-type Pitot tubes, and to enhance the quality of the GHG emission measurements in the smokestack. The 3D Pitot tubes can measure both axial and non-axial velocity components of a flow, whereas the S-type Pitot tubes can measure only the axial velocity component. The averaged axial velocity of the stack gas as measured by this instrument has expanded uncertainty of 3.3% (P = 95%, k = 2) for both prism and sphere Pitot tubes.

Techno-environmental feasibility of wood waste derived fuel for cement production

Turning waste-to-resources is one of the key scientific interests in recent years, especially within industrial symbiosis networks in order to reduce the waste management problem and associated environmental consequences, improve materials efficiency and conserve natural resources. Considering global concern over fossil fuel burning and CO2 emission, engineered fuels are increasingly used in cement production. The techno-environmental feasibility of using post-consumer wood derived fuel (WDF) in practical application is rarely reported. This study comprehensively evaluated the process feasibility and environmental compliances of utilizing WDF as an alternative fuel in the co-combustion process. The results revealed that physical parameters of WDF met the required fuel standards, and the air emissions by continuous emission measurements also met the specified limits and comparable to the baseline. The stack emission parameters monitored including particulates, dioxin, mercury, cadmium and thallium, and other heavy metals were about 60%, 2%, 21%, 6% and 7% of the specified limits. In addition to significantly reducing CO2 emission (16% for using 20% WDF as co-fuel), the characteristics, of the flue gas as monitored by continuous emission monitoring and periodic stack emission at the cement plant, and the produced clinker quality were also not affected by the use of WDF. These have demonstrated the suitability of WDF as co-fuel for cement production.

Comparative study of gas-analyzing systems designed for continuous monitoring of TPP emissions

Determining the composition of combustion products is important in terms of both control of emissions into the atmosphere from thermal power plants and optimization of fuel combustion processes in electric power plants. For this purpose, the concentration of oxygen, carbon monoxide, nitrogen, and sulfur oxides in flue gases is monitored; in case of solid fuel combustion, fly ash concentration is monitored as well. According to the new nature conservation law in Russia, all large TPPs shall be equipped with continuous emission monitoring and measurement systems (CEMMS) into the atmosphere. In order to ensure the continuous monitoring of pollutant emissions, direct round-the-clock measurements are conducted with the use of either domestically produced or imported gas analyzers and analysis systems, the operation of which is based on various physicochemical methods and which can be generally used when introducing CEMMS. Depending on the type and purposes of measurement, various kinds of instruments having different features may be used. This article represents a comparative study of gas-analysis systems for measuring the content of polluting substances in exhaust gases based on various physical and physicochemical analysis methods. It lists basic characteristics of the methods commonly applied in the area of gas analysis. It is proven that, considering the necessity of the long-term, continuous operation of gas analyzers for monitoring and measurement of pollutant emissions into the atmosphere, as well as the requirements for reliability and independence from aggressive components and temperature of the gas flow, it is preferable to use optical gas analyzers for the aforementioned purposes. In order to reduce the costs of equipment comprising a CEMMS at a TPP and optimize the combustion processes, electrochemical and thermomagnetic gas analyzers may also be used.

Design considerations for a continuous emission measurement system for pressure type bag houses

Measurement of the outlet particulate concentration on pressure-type bag filters, whether intermittent or continuous, has been avoided in South Africa as cumbersome and possibly inaccurate. A system based on the requirements of the US EPA’s method 5D was however recently designed and installed on three pressure-type reverse air filters serving ferro-chrome electric arc furnaces in order to allow comparison with the legal emission concentration limits for this type of furnace. This paper reports on the design considerations and design process of this system.

Estimating and comparing greenhouse gas emissions with their uncertainties using different methods: A case study for an energy supply utility

Energy supply utilities release significant amounts of greenhouse gases (GHGs) into the atmosphere. It is essential to accurately estimate GHG emissions with their uncertainties, for reducing GHG emissions and mitigating climate change. GHG emissions can be calculated by an activity-based method (i.e., fuel consumption) and continuous emission measurement (CEM). In this study, GHG emissions such as CO2, CH4, and N2O are estimated for a heat generation utility, which uses bituminous coal as fuel, by applying both the activity-based method and CEM. CO2 emissions by the activity-based method are 12–19% less than that by the CEM, while N2O and CH4 emissions by the activity-based method are two orders of magnitude and 60% less than those by the CEM, respectively. Comparing GHG emissions (as CO2 equivalent) from both methods, total GHG emissions by the activity-based methods are 12–27% lower than that by the CEM, as CO2 and N2O emissions are lower than those by the CEM. Results from uncertainty estimation show that uncertainties in the GHG emissions by the activity-based methods range from 3.4% to about 20%, from 67% to 900%, and from about 70% to about 200% for CO2, N2O, and CH4, respectively, while uncertainties in the GHG emissions by the CEM range from 4% to 4.5%. For the activity-based methods, an uncertainty in the Intergovernmental Panel on Climate Change (IPCC) default net calorific value (NCV) is the major uncertainty contributor to CO2 emissions, while an uncertainty in the IPCC default emission factor is the major uncertainty contributor to CH4 and N2O emissions. For the CEM, an uncertainty in volumetric flow measurement, especially for the distribution of the volumetric flow rate in a stack, is the major uncertainty contributor to all GHG emissions, while uncertainties in concentration measurements contribute a little to uncertainties in the GHG emissions.Implications:Energy supply utilities contribute a significant portion of the global greenhouse gas (GHG) emissions. It is important to accurately estimate GHG emissions with their uncertainties for reducing GHG emissions and mitigating climate change. GHG emissions can be estimated by an activity-based method and by continuous emission measurement (CEM), yet little study has been done to calculate GHG emissions with uncertainty analysis. This study estimates GHG emissions and their uncertainties, and also identifies major uncertainty contributors for each method.

Volatilization behavior of Cd and Zn based on continuous emission measurement of flue gas from laboratory-scale coal combustion

The accumulation of toxic metals generated by coal-fired power stations presents a serious threat to the environment. The volatilization behavior of two representative metals (Cd and Zn), and the influence of temperature were investigated during coal combustion. An inductively coupled plasma atomic emission spectrometric (ICP-AES) method was developed to continuously measure the heavy metal concentrations quantitatively in flue gas under combustion conditions in order to track the metal release process. This continuous heavy metal analysis system was implemented by coupling it to two types of high temperature reactors: a bubbling fluidized bed reactor and a fixed bed reactor with diameter of 0.1 m and 0.08 m respectively. For the two metals considered in this study (Cd and Zn), the experimental setup was successfully used to continuously monitor the metal vaporization process during coal combustion independent of reactor design, and at different temperatures. Cd is more easily vaporized than Zn during coal combustion. Temperature significantly influences the metal vaporization process. In general, the higher the temperature, the higher the metal vaporization, although the vaporization is not proportional to temperature. In addition to the experimental study, a thermodynamic calculation was carried out to simulate the heavy metal speciation during coal combustion process. The theoretical volatilization tendency is consistent with the experiment. The thermodynamic calculation identified the formation of binary oxides retarding heavy metal vaporization.

Continuous Ammonia Emission Measurements from a Commercial Beef Feedyard in Texas

Ammonia emissions from cattle feedlots pose the potential to react with other compounds such as oxides of nitrogen and sulfur, which lead to detrimental environmental effects. Ambient ammonia (NH3) concentrations were measured continuously at a beef cattle feedyard for 12 months beginning in March 2007. Concentrations were measured every 5 min, 24 hours per day, at a sample intake height of 3.3 m using a chemiluminescence analyzer. On-site weather data were collected concurrently. Modeled emissions of NH3 were compared with the mass balance of N for the feedyard. Mean annual NH3 concentrations were 0.57 ppm, with a monthly average low of 0.37 ppm in December 2007 and a monthly average high of 0.77 ppm in August 2007. Flux densities were calculated using a backward Lagrangian stochastic model (WindTrax 2.0.7.8). Mean annual flux density was 70.7 g m-2 s-1 (2.2 kg m-2 year-1). Mean monthly flux density ranged from 42.7 to 123.1 g m-2 s-1 (0.11 to 0.32 kg m-2 month-1) in November and April 2007, respectively. Both concentration and flux density had a diel distribution with minima during the nighttime hours and maxima during the early afternoon. On an annual basis, 48.8% of fed N was volatilized as NH3. The inverse modeled daily ammonia production per head was 85.3 g NH3-N (head fed)-1 d-1.

Variations in geoacoustic emissions in a deep borehole and its correlation with seismicity

Continuous geoacoustic emission (GAE) measurements were acquired using a three-component geophone placed in a borehole at a depth of near 1000 m at Petropavlovsk-Kamchatsky starting in August 2000. Using geophones consisting of magneto-elastic crystal ferromagnetic sensors, and installed at such a depth allows measurement of natural geoacoustic background with signal amplitude less than 1×10 -4 m/s 3 in frequency band from 3 to 1500 Hz. According to the data from a 4-year survey period the characteristics of diurnal geoacoustic variations change before every earthquake with MLH≥ 5.0 that occurs at a distance of less than 300 km from the observation point or before each earthquake with MLH≥5.5 occurring at distance R≤550 km from the observation point. The changes in GAE regime correlate with the strongest earthquakes that occurred during survey period. Measurements of the natural electromagnetic field of the Earth were carried out simultaneously with the help of an underground electric antenna. The behavior of GAE in aseismic periods appears to be related to the effect of diurnal variations of the natural electromagnetic field.

Optimisation and validation of the intermittent measurement method to determine ammonia emissions from livestock buildings

In previous studies, a method to reduce the high cost of continuous ammonia emission measurements by using the expensive equipment in several buildings for short periods was developed. Further optimisation and validation of the method of “intermittent measurements” to estimate the ammonia yearly emission from pig houses, based on a limited number of measuring days, are described. The method is tested and improved with new data from three different pig houses. The method of “intermittent measurements” models the relationship between ammonia emission and easily measurable variables such as in- and outdoor temperatures, ventilation rate and weight of the animals. The parameters of the emission model are determined for an individual farm in a time variant manner. They are based on frequent ammonia measurements in combination with the easily measured variables from a limited number of days over a certain time interval. For all other days throughout the year, the emission of ammonia is not measured, but, by using the model, it is calculated from the easily measured variables. In previous studies, the parameters in the emission model for a specific building were calculated only once a year with the data of all selected measuring days throughout the year. In this study, the ammonia emission was modelled in a more precise, stepwise manner such that model parameters were calculated over shorter time periods, such as 70 days. This resulted in an optimised procedure in which, for fattening pigs, each fattening period was modelled in two parts: the first part from day 1 to day 70 and the second part from day 70 to the end of the fattening period. The adapted method was tested on data from seven fattening periods originating from three different pig houses. The accuracy of the method was obtained by evaluating the difference between the ammonia emission calculated from the model with the measured total ammonia emission, sampled every 12 min over a whole fattening period. With 4 measuring days per fattening period, a maximum model error of less than 10% was achieved for all datasets; while previous method with fixed model parameters throughout the year on the new validation datasets resulted sometimes in errors above 25%.

HDE 245059: A WEAK-LINED T TAURI BINARY REVEALED BYCHANDRAAND KECK

We present the Chandra High Energy Transmission Grating Spectrometer and Keck observations of HDE 245059, a young weak-lined T Tauri star (WTTS), member of the pre-main-sequence group in the λ Orionis Cluster. Our high spatial resolution, near-infrared observations with Keck reveal that HDE 245059 is in fact a binary separated by 087, probably composed of two WTTS based on their color indices. Based on this new information we have obtained an estimate of the masses of the binary components; ≈3 M☉ and ≈2.5 M☉ for the north and south components, respectively. We have also estimated the age of the system to be ≈2–3 Myr. We detect both components of the binary in the zeroth-order Chandra image and in the grating spectra. The light curves show X-ray variability of both sources and in particular a flaring event in the weaker southern component. The spectra of both stars show similar features: a combination of cool and hot plasma as demonstrated by several iron lines from Fe xvii to Fe xxv and a strong bremsstrahlung continuum at short wavelengths. We have fitted the combined grating and zeroth-order spectrum (considering the contribution of both stars) in XSPEC. The coronal abundances and emission measure distribution for the binary have been obtained using different methods, including a continuous emission measure distribution and a multi-temperature approximation. In all cases we have found that the emission is dominated by plasma between ∼8 and ∼15 MK a soft component at ∼4 MK and a hard component at ∼50 MK are also detected. The value of the hydrogen column density was low, NH ∼ 8 × 1019 cm−2, likely due to the clearing of the inner region of the λ Orionis cloud, where HDE 245059 is located. The abundance pattern shows an inverse first ionization potential effect for all elements from O to Fe, the only exception being Ca. To obtain the properties of the binary components, a 3-T model was fitted to the individual zeroth-order spectra using the abundances derived for the binary. We have also obtained several line fluxes from the grating spectra. The fits to the triplets show no evidence of high densities. In conclusion, the X-ray properties of the weak-lined T Tau binary HDE 245059 are similar to those generally observed in other weak-lined T Tau stars. Although its accretion history may have been affected by the clearing of the interstellar material around λ Ori, its coronal properties appear to not have been strongly modified.

The XMM-Newton extended survey of the Taurus molecular cloud (XEST)

The Taurus Molecular Cloud (TMC) is the nearest large star-forming region, prototypical for the distributed mode of low-mass star formation. Pre-main sequence stars are luminous X-ray sources, probably mostly owing to magnetic energy release. Aims. The XMM-Newton Extended Survey of the Taurus Molecular Cloud (EST) presented in this paper surveys the most populated =5 square degrees of the TMC, using the XMM-Newton X-ray observatory to study the thermal structure, variability, and long-term evolution of hot plasma, to investigate the magnetic dynamo, and to search for new potential members of the association. Many targets are also studied in the optical, and high-resolution X-ray grating spectroscopy has been obtained for selected bright sources. Methods. The X-ray spectra have been coherently analyzed with two different thermal models (2-component thermal model, and a continuous emission measure distribution model). We present overall correlations with fundamental stellar parameters that were derived from the previous literature. A few detections from Chandra observations have been added. Results. The present overview paper introduces the project and provides the basic results from the X-ray analysis of all sources detected in the XEST survey. Comprehensive tables summarize the stellar properties of all targets surveyed. The survey goes deeper than previous X-ray surveys of Taurus by about an order of magnitude and for the first time systematically accesses very faint and strongly absorbed TMC objects. We find a detection rate of 85% and 98% for classical and weak-line T Tau stars (CTTS resp. WTTS), and identify about half of the surveyed protostars and brown dwarfs. Overall, 136 out of 169 surveyed stellar systems are detected. We describe an X-ray luminosity vs. mass correlation, discuss the distribution of X-ray-to-bolometric luminosity ratios, and show evidence for lower X-ray luminosities in CTTS compared to WTTS. Detailed analysis (e.g., variability, rotation-activity relations, influence of accretion on X-rays) will be discussed in a series of accompanying papers.

Coronal abundances from high-resolution X-ray data: The case of Algol

We discuss the determination of elemental abundances from high resolution X-ray data. We emphasize the need for an accurate determination of the underlying temperature structure and advocate the use of a line ratio method which allows us to utilize, first, the strongest lines observed in the X-ray spectra, and second, lines that span a rather wide temperature range. We point out the need to use continuous emission measure distributions and show via example that modeling in terms of individual temperature components yields errors of more than 50%. We stress the need to derive differential emission measure distributions based on physical assumptions and considerations. We apply our methods to the Chandra LETGS spectrum of Algol and show that nitrogen is considerably enhanced compared to cosmic abundances by a factor of 2 while carbon is depleted by at least a factor of 25. Iron, silicon, and magnesium, are all depleted compared to cosmic abundances, while the noble gas neon has the relatively highest abundance.

Time-Variability of NOxEmissions from Portland Cement Kilns

Due to the presence of autocorrelation between sequentially measured nitrogen oxide (NOx) concentrations in stack gas from portland cement kilns, the determination of the average emission rates and the uncertainty of the average has been improperly calculated by the industry and regulatory agencies. Documentation of permit compliance, establishment of permit levels, and the development and testing of control techniques for reducing NOx emissions at specific cement plants requires accurate and precise statistical estimates of parameters such as means, standard deviations, and variances. Usual statistical formulas such as for the variance of the sample mean only apply if sequential measurements of NOx emissions are independent. Significant autocorrelation of NOx emission measurements revealed that NOx concentration values measured by continuous emission monitors are not independent but can be represented by an autoregressive, moving average (ARMA) time series. Three orders of time-variability of NOx emission rates were determined from examination of continuous emission measurements from several cement kilns. Long-term variations are related to changes in process control, feed composition, fuel composition, and types of product produced and are reflected by nonperiodic drift in the time series. Intermediate-term variations result from changes in process control and operator technique. Very short-term variations, which are not normally visible due to the averaging process applied to data collection, are related to the dynamics of the flame. Autocorrelation effects within the emission rates extend over a period of 8−10 h. The high levels of autocorrelation observed between sequential readings result in underestimating the variance of the average emission rate unless autocorrelation effects are considered. Although thousands of NOx measurements may be recorded, autocorrelation of sequential measurements implies that many of them are redundant.

Corona(e) of AR Lacertae. I. The Temperature and Abundance Distribution

view Abstract Citations (92) References (43) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Corona(e) of AR Lacertae. I. The Temperature and Abundance Distribution Singh, K. P. ; White, N. E. ; Drake, S. A. Abstract X-ray spectra of the RS CVn binary AR Lac, obtained from simultaneous observations with the ROSAT PSPC and the ASCA SIS and GIS detectors, have been analyzed to study the coronal temperature and abundance distribution. The spectra were jointly fitted with plasma emission models to the following possible temperature distributions: (a) one with discrete multitemperature emission components, (b) a continuous emission measure with a power-law dependence on temperature, and (c) a continuous emission distribution parameterized by the sum of a sixth-order Chebyshev polynomial. We find that (i) solar abundance plasma models with either discrete or continuous emission measure (CEM) distributions are rejected, (ii) the best fit is obtained with a two-temperature (2T) plasma emission model with an underabundance of the elements 0, Mg, Si, S, Ar, Ca, and Fe by a factor of 3-4 relative to the solar photospheric values, and (iii) the best-fit CEM distribution also has similarly reduced abundances but fits the data less well than the 2T model. These results are confirmed even when the Fe-L region, which is subject to uncertainties in the atomic physics, is excluded from the fit. We consider optical depth effects as unlikely to be the explanation for the observed weakness of the line complexes relative to the continuum. Analysis of the spectral data during the primary and secondary eclipses shows that the emission measure of the high-temperature component in the 2T models appears to be more affected by the primary eclipse than the low-temperature component, suggesting that part of the former is concentrated in structures that are spatially more compact. Publication: The Astrophysical Journal Pub Date: January 1996 DOI: 10.1086/176695 Bibcode: 1996ApJ...456..766S Keywords: STARS: BINARIES: ECLIPSING; STARS: ABUNDANCES; STARS: CORONAE; STARS: INDIVIDUAL CONSTELLATION NAME: AR LACERTAE; X-RAYS: STARS full text sources ADS | data products SIMBAD (5) HEASARC (1) Related Materials (1) Part 2: 1996ApJ...473..470S

X-Ray Emission from the Sun in Its Youth and Old Age

We have obtained ROSAT PSPC (Roentgen Satellite Position Sensitive Proportional Counter) pointed observations of two nearby G stars of ages 70 Myr and 9.5 Gyr that are of unique importance as proxies for the Sun at the two extremes of its main-sequence evolutionary lifetime. The younger star, HD 129333 (EK Dra; G0 V), a rapid rotator with a 2.7 day period, is a strong source with an X-ray luminosity L(x)(0.2-2.4 keV) = (7.5-11.5) x 10(exp 29) erg/s. Modeling suggests a two-temperature corona with T(1) = (2.0 +/- 0.3) x 10(exp 6) K and T(2) = (9.7 +/- 0.3) x 10(exp 6) K (formal uncertainties). A continuous emission measure distribution, increasing to higher temperatures and with a cutoff at (20-30) x 10(exp 6) K, yields even better fits to the data. The old star, beta Hyi (HR 98; G2 IV), represents the Sun in the future, near the end of its hydrogen-core burning stage, when it should be rotating more slowly (present P(rot) = 25.4 day) and should have lower levels of activity. The ROSAT measurements yield L(x) = (0.9-3.0) x 10(exp 27) ergs/s and a rather cool, single coronal temperature of T = (1.7 +/- 0.4) x 10(exp 6) K. For comparison, the Sun has L(x) approx. equal to 2 x 10(exp 27) ergs/s and a coronal temperature of about T = 2 x 10(exp 6) K. These stars provide information on the decline of the stellar (and specifically solar) magnetic activity from extreme youth to old age. HD 129333 is also important in that it yields an estimate of the solar soft X-ray flux in the early solar system at the epoch of the terminal stages of planetary accretion.

A study of coronal X-ray emission from short-period Algol binaries

A study of X-ray emission from five short-period Algol-type binaries based on observations with Advanced Satellite for Cosmology and Astrophysics (ASCA) and ROSAT is presented. We have observed RZ Cas with both satellites, and beta Per, U Cep, delta Lib, and TW Dra with ROSAT. Significant intensity variations are seen in the X-ray emission from RZ Cas, U Cep, TW Dra, and delta Lib. These variations seem unrelated to the eclipsing behavior of these systems and are probably due to either rotational modulation of compact active regions on the surfaces of the chromospherically active secondary components or to flaring activity in the systems. The spectra of all but one of the systems require the presence of at least two discrete plasma components with different temperatures (0.6 - 0.7 keV, and approximately 2 keV) and the abundances of the medium-Z elements 20% - 50% of the solar photospheric values. The high resolving power and signal-to-noise ratio of the ASCA spectra allow us to individually constrain the coronal abundances of O, Ne, Mg, Si, S, and Fe in RZ Cas. We demonstrate that, if we use the elemental abundances and temperatures obtained from the analysis of their ASCA spectra as (fixed) inputs, to fit the ROSAT PSPC spectra well requires the presence of a third component (kT approximately 0.2 - 0.3 keV) in RZ Cas and beta Per. A continuous emission measure model of the power-law type (EM(T) variesas (T/T(sub max)(sup alpha)) generally gives a poor fit to the ASCA and ROSAT data on most sources. Circumstellar or circumbinary absorbing matter seems to be present in some of these systems, as indicated by the variable total column density needed to fit their X-ray spectra.