Objective and subjective evaluation of power plants and their non-radioactive emissions using the analytic hierarchy process

Non-nuclear power plant emissions are of great concern to the public and to scientists alike. As energy demand tends to rise rapidly, especially in the developing countries, the negative effects to human health and to the environment from gaseous emissions together with hazardous particulate matter released by power plants can no longer be ignored.     

Technological,economic and sustainability evaluation of power plants using the Analytic Hierarchy Process

Complexity of power plant evaluation is steadily rising, as more criteria are involved in the overall assessment while evaluation data change rapidly. Apart from evaluating several aspects of power plants separately, a multicriteria analysis based on hierarchically structured criteria is necessary, so as to address the overall assessment of power plants according to the technological, economic and sustainability aspects. For this reason, in this paper, ten types of power plant are evaluated using nine end node criteria properly structured under the Analytical Hierarchy Process. Moreover, pairwise comparisons allow for accurate subjective criteria weighting.     

Enzymic production of feruloyl xylo-oligosaccharides from corn cobs by a family 10 xylanase from Thermoascus aurantiacus

Feruloyl xylo-oligosaccharides (FeXOSs) were obtained from corn cobs (CCs) by treatment with a Thermoascus aurantiacus family 10-β-d-endoxylanase. CCs subjected to a sonication (ST-CC) or an autoclave treatment in order to enhance enzymic access and FeXOS production. Enzymic FeXOS production was increased by CCs thermal treatment up to 3.5 times. The kinetic parameters K_E and V_max, describing enzyme-dependent production rates of FeXOSs from CCs, were estimated at 130±20 nM and 290±10 nM h⁻¹, respectively. The reaction parameters affecting the FeXOS production, such as substrate concentration, enzyme loading and reaction time, have been investigated. The maximum FeXOS production was observed after 24 h incubation of 100 g L⁻¹ AT-CC with 570 nM xylanase. The obtained yield was 12 μmol of FeXOSs per gram of CC.     

Magnetic resonance spin-labeling perfusion imaging of synovitis in inflammatory arthritis at 3.0 T

Objective  The aim of this study was to test the feasibility of arterial spin labeling (ASL) perfusion imaging of synovitis in inflammatory joint diseases on a clinical 3.0 T whole-body scanner. Materials and methods  Fifteen patients (geometric mean 47 years, range 8–69 years) with different types of inflammatory arthritis of the finger or wrist joints participated in the study. In addition to conventional spin-echo and dynamic contrast-enhanced FLASH3D sequences, a novel spin-labeling technique (FAIR-TrueFISP) for quantitative assessment of tissue perfusion was applied. Perfusion maps were calculated pixel-wise by means of the extended Bloch equations. Results  Perfusion maps showed good image quality with clear visualization of hyperaemia in synovitis. The computed perfusion maps corresponded best to subtraction images of the dynamic series from 30 to 60 s after contrast-medium injection. The quantitative perfusion values of synovitis showed a good correlation with the disease activity. Perfusion values for inflamed synovium in phase of high activity were up to 230 ml/100 g tissue/min. Conclusion  The proposed modality allows for the assessment of disease activity in arthritis without the application of contrast-medium offering a new tool for therapy monitoring. As the technique provides quantitative information on hyperaemia, it potentially offers new insights in the pathophysiology of arthritic diseases.     

Controlling Intercell Interference in CDMA-based Fixed Wireless Networks Through Multirate Techniques

A number of research works have suggested a possible capacity advantage when employing direct sequence-code division multiple access (DS-CDMA) instead of the more common time division multiple access option for fixed broadband wireless access networks operating at millimeter-waves. The choice of this multiple access scheme, which, up to now, has not been foreseen by recent WiMax (worldwide interoperability for microwave access) standards, exhibits an improved performance in terms of cochannel interference in the upstream, even though it experiences higher interference in the downstream. The present paper focuses on enhancing the bottleneck downstream performance of fixed wireless networks by proposing a methodology for controlling the signal-to-interference ratio throughout the cell, so that all subscribers meet the given interference quality-of-service specifications. This is accomplished by exploiting the properties of a combination of multirate CDMA techniques. The paper describes a simple policy for code assignment, which is proved to be optimal, incorporating the effect of rain fading over multiple paths. The performance of the algorithm is tested against single code DS-CDMA both under long term channel statistics (static code assignment) and under dynamic channel effects (dynamic code assignment). The first test verifies the compliance of all sector subscribers with more demanding SIR specifications, while the second yields a significant improvement in terms of resource utilization.     

A Modified Loo Model with Partially Blocked and Three Dimensional Multipath Scattering: Analysis,Simulation and Validation

This paper presents a novel mobile fading channel model, belonging to the class of Loo models, in which the multipath power arrives both in three dimensions (3-D) and in two angular sectors at the azimuth receiver’s plane. Moreover shadowing affects the amplitude of the line of sight (LOS) component, making it time varying and following a lognormal distribution, as required for a Loo model. The Doppler power spectral density (PSD) is analytically calculated, after Fourier transforming the closed form autocorrelation function. Afterwards exact solutions for the probability density function (PDF) of the envelope and phase are presented. What follows are approximate solutions for the second order statistics, i.e. the level crossing rate (LCR) and the average duration of fades (ADF’s). A new, appropriate for 3-D scattering cases, deterministic simulation scheme is developed, which implements the analytical model on a digital computer and is used to test the validity of the approximate solutions. Moreover the deterministic model is thoroughly investigated for all the possible cases, in terms of its convergence to the analytical one. Finally a curve fitting of the LCR to real world data, drawn from channel measurements, will demonstrate the flexibility and usefulness of the modified Loo model.     

Integrated Management of Non-conventional Water Resources in Anhydrous Islands

Anhydrous islands are dependent either on non-conventional water resources, such as desalinated seawater or reclaimed water from wastewater, or on water importation from the mainland. The latter option is often expensive and non-sustainable. Desalinated water can be used for potable and non-potable water applications, while reclaimed water can be used for non-potable water applications. Thus all water needs can be satisfied by an optimal blend of desalinated and reclaimed water. It is important to calculate the optimal capacities and locations of seawater desalination plants, wastewater treatment plants and water reclamation plants, and to estimate the water/wastewater conveyance system, in order to minimise water production and distribution costs. Mathematical modelling and optimisation techniques can be employed for calculating the optimum scenario: the satisfaction of all water needs at minimum cost. In this article, we have estimated the water demands taking into account water quality for the anhydrous Greek island of Syros, in the Aegean Sea. Syros has been subdivided into 6 regions, taking into account geographical and population distribution criteria. All water needs are to be satisfied by desalinated seawater and reclaimed water. A mixed-integer linear programming algorithm is used here to calculate the optimal scenario (location and capacities of desalination plants and wastewater treatment and water reclamation plants, as well as the desalinated water, reclaimed water and wastewater conveyance infrastructure needed) by minimising the annualised total cost including capital and operating costs.     

A High Volume Apparatus for the Condensational Growth of Ultrafine Particles for Inhalation Toxicological Studies

A high volume (2500 LPM) system for the condensational growth of ultrafine particles was developed and evaluated using indoor air as a test aerosol. The main features of this system are the following: (a) ultrafine particles grow condensationally to supermicron sizes using high purity deionized water as a condensing medium; (b) the supersaturation ratio is adjustable and can be precisely controlled; (c) the system can operate for a wide range of ambient air temperature and relative humidity conditions; and (d) a thermal dryer is used to return the condensationally grown particles back to their original size. Restoring the original ambient size distribution and preserving the composition of the ambient ultrafine particles is very important for inhalation studies. The system is fully automated and has computerized feedback controls. In addition, saturation of the aerosol with water vapor occurs at close to ambient temperatures to minimize particle losses of volatile components. Saturation of sample air is obtained using a direct steam-injecting, fully modulating electric humidifier. The sample air after saturation is drawn through the supersaturator, which is a refrigerant-to-air heat exchanger and is cooled down to obtain the desirable supersaturation ratio. Supersaturation ratios can be precisely adjusted, with the optimum operational level found to be in the range of 2 to 3. The performance of the system was evaluated as a function of critical operation parameters, including the supersaturation ratio as well as the saturation and supersaturation temperatures. A series of virtual and conventional impactors was used to characterize the condensational growth of ultrafine particles. This new high volume apparatus was shown to grow ambient ultrafine particles to supermicron sizes with a particle size growth of approximately 1.8 w m. Particle losses in the system were found to be minimal (about 10%). The thermal dryer was used successfully to restore the grown particles back to their original size distribution. Particle concentration, aerosol temperature, and residence time (aerosol flow) are key parameters shown to affect the performance of the thermal dryer was used successfully to restore the grown particles back to their original size distribution. Particle concentration, aerosol temperature, and residence time (aerosol flow) are key parameters shown to affect the performance of the thermal dryer.     

Non-invasive pulmonary perfusion assessment in young patients with cystic fibrosis using an arterial spin labeling MR technique at 1.5 T

Object  

To assess lung perfusion in young patients with cystic fibrosis (CF) using an arterial spin labeling (ASL) technique.