The effects of wastewater step-feeding (SF) on the performance of horizontal subsurface flow constructed wetlands (HSF CWs) are numerically investigated. The purpose is to check if this alternative ...feeding technique increases the ability of HSF CWs to remove pollutants. Two methodologies are used: Initially, the tanks-in-series (TIS) methodology, based on the finite volume method (FVM), is analyzed using the volumetric degradation coefficient λ. In this case, the operation of a CW is similar to a series of continuous stirred-tank reactors (CSTRs) operating under steady conditions. Then, the step-feeding (SF) procedure is presented, in which the CW is operated like a plug flow reactor (PFR). For the numerical investigation, the available experimental data for five existing HSF CWs are used. The results show that SF does not improve the performance of HSF CWs in removing biochemical oxygen demand (BOD) operating under Mediterranean conditions. When the HSF CWs operate without the SF procedure, the performance is between 55 and 81% for the TIS method and 60 and 89% for the PFR method, while the ability of the CW tank to remove the BOD decreases and varies from 48 to 79% (TIS) and from 54 to 86% (PFR), respectively.
Search for chameleons with CAST Anastassopoulos, V.; Arik, M.; Aune, S. ...
Physics letters. B,
10/2015, Letnik:
749, Številka:
C
Journal Article
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In this work we present a search for (solar) chameleons with the CERN Axion Solar Telescope (CAST). This novel experimental technique, in the field of dark energy research, exploits both the ...chameleon coupling to matter (βm) and to photons (βγ) via the Primakoff effect. By reducing the X-ray detection energy threshold used for axions from 1 keV to 400 eV CAST became sensitive to the converted solar chameleon spectrum which peaks around 600 eV. Even though we have not observed any excess above background, we can provide a 95% C.L. limit for the coupling strength of chameleons to photons of βγ≲1011 for 1<βm<106.
This paper presents an extensive parametric study on the inelastic response of eight reinforced concrete (RC) planar frames which are subjected to forty five sequential ground motions. Two families ...of regular and vertically irregular (with setbacks) frames are examined. The first family has been designed for seismic and vertical loads according to European codes while the second one only for vertical loads, to study structures which have been constructed before the introduction of adequate seismic design code provisions. The whole range of frames is subjected to five real seismic sequences which are recorded by the same station, in the same direction and in a short period of time, up to three days. In such cases, there is a significant damage accumulation as a result of multiplicity of earthquakes, and due to lack of time, any rehabilitation action is impractical. Furthermore, the examined frames are also subjected to forty artificial seismic sequences. Comprehensive analysis of the created response databank is employed in order to derive important conclusions. It is found that the sequences of ground motions have a significant effect on the response and, hence, on the design of reinforced concrete frames. Furthermore, it is concluded that the ductility demands of the sequential ground motions can be accurately estimated using appropriate combinations of the corresponding demands of single ground motions.
In this case report we describe a case of propofol infusion syndrome in an adult after a short-term infusion of large-dose propofol during a neurosurgical procedure. Large-dose propofol (9 ...mg.kg(-1).h(-1)) was given for only 3 h during surgery and was followed by a small-dose infusion (2.3 mg.kg(-1).h(-1)) for 20 h postoperatively. The patient had also received large doses of methylprednisolone. He developed a marked lactic acidosis with mild biological signs of renal impairment and rhabdomyolysis but no cardiocirculatory failure. There were no other evident causes of lactic acidosis as documented by laboratory data. We believe this is the first report of reversible lactic acidosis associated with a short duration of large-dose propofol anesthesia.
A semi-analytical plane elasticity solution of the circular hole with diametrically opposite notches in a homogeneous and isotropic geomaterial is presented. This solution is based on: (i) the ...evaluation of the conformal mapping function of a hole of prescribed shape by an appropriate numerical scheme and (ii) the closed-form solutions of the Kolosov-Muskhelishvili complex potentials. For the particular case of circular notches - which resemble to the circular cavity breakout in rocks - it is demonstrated that numerical results pertaining to boundary stresses and displacements predicted by the finite differences model FLAC2D, as well as previous analytical results referring to the stress-concentration-factor, are in agreement with analytical results. It is also illustrated that the solution may be easily applied to non-rounded diametrically opposite notch geometries, such as 'dog-eared' breakouts by properly selecting the respective conformal mapping function via the methodology presented herein. By employing a stress-mean-value brittle failure criterion that takes into account the stress-gradient effect in the vicinity of the curved surfaces in rock as well as the present semi-analytical solution, it is found that a notched hole, e.g. borehole or tunnel breakout, may exhibit stable propagation. The practical significance of the proposed solution lies in the fact that it can be used as a quick-solver for back-analysis of borehole breakout images obtained in situ via a televiewer for the estimation of the orientation and magnitude of in situ stresses and of strain-stress measurements in laboratory tests.
► Modeling of BOD removal in horizontal subsurface flow constructed wetlands. ► Use of MODFLOW-MT3DMS set of codes – validation with experimental data. ► Evaluation of first-order decay coefficient ...λ. ► Dependence of decay coefficient λ on temperature and HRT. ► Scenarios for various temperature, HRT, vegetation and porous media conditions.
A numerical modeling effort of flow and Biochemical Oxygen Demand (BOD) fate in horizontal subsurface flow (HSF) constructed wetlands (CWs), under Mediterranean conditions, is presented. The Visual MODFLOW family computer code, based on the finite difference method, was used for the numerical simulation of flow in five pilot-scale HSF CW units containing various vegetation and porous material types, and operating under various temperature and hydraulic residence time (HRT) conditions. BOD fate and transport was simulated using the MT3DMS computer code. Experimental data from these CW units were used in estimating the BOD removal coefficient, required in the above modeling effort. Values of this removal coefficient were found to depend on temperature and HRT. Relations are presented for the prediction of this coefficient. The model was calibrated and verified using the measured BOD concentrations, and was used in test runs comparing performance under various vegetation, porous media size, temperature and HRT conditions. Model performance was found acceptable, indicating its usefulness in the simulation of BOD fate in CWs and in the design of these facilities.
Hypothetical low-mass particles, such as axions, provide a compelling explanation for the dark matter in the universe. Such particles are expected to emerge abundantly from the hot interior of stars. ...To test this prediction, the CERN Axion Solar Telescope (CAST) uses a 9 T refurbished Large Hadron Collider test magnet directed towards the Sun. In the strong magnetic field, solar axions can be converted to X-ray photons which can be recorded by X-ray detectors. In the 2013-2015 run, thanks to low-background detectors and a new X-ray telescope, the signal-to-noise ratio was increased by about a factor of three. Here, we report the best limit on the axion-photon coupling strength (0.66 × 10-10 GeV-1 at 95% confidence level) set by CAST, which now reaches similar levels to the most restrictive astrophysical bounds.
Objective – Patients with definite multiple sclerosis (MS) were tested for autonomic nervous system (ANS) dysfunction using clinical symptomatology criteria and non‐invasive laboratory testing. ...Exactly 45.45% of patients exhibited subjective symptoms of autonomic dysfunction and 42.42% of patients had abnormal laboratory tests results.
Methods – The sympathetic ANS tests were abnormal in 30.3% of MS patients and the parasympathetic ANS tests were abnormal in 18.18% of MS patients. The most sensitive test for the presence of autonomic dysfunction was the sympathetic skin response.
Conclusion – Autonomic dysfunction was often subclinical and we conclude that it is preferable to combine several tests for a more thorough and accurate evaluation of the ANS impairment in MS.
Damage detection at early cracking stages in
shear-critical reinforced concrete beams, before further
deterioration and their inevitable brittle shear failure
is crucial for structural safety and ...integrity. The effectiveness
of a structural health monitoring technique using
the admittance measurements of piezoelectric transducers
mounted on a reinforced concrete beam without
shear reinforcement is experimentally investigated.
Embedded “smart aggregate” transducers and externally
bonded piezoelectric patches have been placed in arrays
at both shear spans of the beam. Beam were tested till total
shear failure and monitored at three different states;
healthy, flexural cracking and diagonal cracking. Test results
showed that transducers close to the critical diagonal
crack provided sound and graduated discrepancies between
the admittance responses at the healthy state and
thedamage levels.Damage assessment using statistical indices
calculated from the measurements of all transducers
was also attempted. Rational changes of the index values
were obtained with respect to the increase of the damage.
Admittance responses and index values of the transducers
located on the shear span where the critical diagonal
crack formed provided cogent evidence of damage. On the
contrary, negligible indication of damage was yielded by
the responses of the transducers located on the other shear
span, where no diagonal cracking occurred.
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