Model based prediction of the clogging of an anaerobic fixed bed reactor

2002 ◽  
Vol 45 (4-5) ◽  
pp. 255-262 ◽  
Author(s):  
J. Harmand ◽  
F. Miens ◽  
T. Conte ◽  
P. Gras ◽  
P. Buffière ◽  
...  
Keyword(s):  
Constrained Optimization ◽  
Fixed Bed ◽  
Optimization Techniques ◽  
Fixed Bed Reactor ◽  
Balance Model ◽  
Liquid Volume ◽  
Nonlinear Constrained Optimization ◽  
Mean Values ◽  
The Mean ◽  
Theoretical Results

This paper presents the use of nonlinear constrained optimization techniques in order to detect and evaluate the degree of clogging in an anaerobic fixed bed reactor. First, experimental results show that the validity of a mass balance model can degrade over the time. Using the available model of the process and nonlinear constrained optimization tools, it is established that these changes can be due to the decrease of the liquid volume into the reactor while the mean values of biomass concentrations increase, leading to the clogging of the reactor. These theoretical results are confirmed experimentally in evaluating the hydraulic retention time of the reactor using a tracer.

scholarly journals Characterizaton of Thermochemical Conversion Processes in a Technical-Scale Fixed-Bed Reactor: Pyrolysis and Gasification

2014 ◽  
Vol 16 (2-3) ◽  
pp. 209 ◽  
Author(s):  
A. Diéguez-Alonso ◽  
A. Anca-Couce ◽  
F. Behrendt
Keyword(s):  
Raw Materials ◽  
Beech Wood ◽  
Fixed Bed ◽  
Product Distribution ◽  
Industrial Applications ◽  
Optimization Techniques ◽  
Fixed Bed Reactor ◽  
Thermochemical Conversion ◽  
Process Conditions ◽  
Process Characterization

<p>Consolidated industrial application of biomass thermochemical conversion processes, such as pyrolysis and gasification, requires the development and application of control and optimization techniques. To this end, on-line process characterization, regarding mainly product distribution and composition under similar conditions as the ones encountered in industrial applications is needed. In the present study, slow pyrolysis and updraft gasification of thermally thick particles in a technical scale fixed-bed reactor are carried out under several process conditions. Different raw materials are used: pine wood chips, beech-wood spheres and cellulose. In pyrolysis, the increasing influence of transport phenomena in the conversion process due to the use of a technical-scale reactor and thermally thick wood particles is analysed through the temperature distribution inside the bed during the process together with the char properties characterization taken from four different positions inside the bed. The influence of process conditions, such as the N<sub>2</sub> flow rate, on the products composition and distribution is also analysed. In gasification, the influence of the air to fuel ratio on the product gas composition is characterized, as well as the qualitative evolution of polycyclic aromatic hydrocarbons (PAH) representative species in the volatiles vapours by applying laser-induced fluorescence (LIF).</p>

scholarly journals Start-up of horizontal anaerobic reactors with sludge blanket and fixed bed for wastewater treatment from coffee processing by wet method

2013 ◽  
Vol 33 (2) ◽  
pp. 353-366 ◽  
Author(s):  
Roberto A. de Oliveira ◽  
Natani M. N. Bruno
Keyword(s):  
Fixed Bed ◽  
Oxygen Demand ◽  
Anaerobic Treatment ◽  
Mean Value ◽  
Treatment System ◽  
Anaerobic Sludge ◽  
Mean Values ◽  
Anaerobic Reactors ◽  
Start Up ◽  
The Mean

In this study it was evaluated the start-up procedures of anaerobic treatment system with three horizontal anaerobic reactors (R1, R2 and R3), installed in series, with volume of 1.2 L each. R1 had sludge blanket, and R2 and R3 had half supporter of bamboo and coconut fiber, respectively. As an affluent, it was synthesized wastewater from mechanical pulping of the coffee fruit by wet method, with a mean value of total chemical oxygen demand (CODtotal) of 16,003 mg L-1. The hydraulic retention time (HRT) in each reactor was 30 h. The volumetric organic loading (VOL) applied in R1 varied from 8.9 to 25.0 g of CODtotal (L d)-1. The mean removal efficiencies of CODtotal varied from 43 to 97% in the treatment system (R1+R2+R3), stabilizing above 80% after 30 days of operation. The mean content of methane in the biogas were of 70 to 76%, the mean volumetric production was 1.7 L CH4 (L reactor d)-1 in the system, and the higher conversions were around at 0.20 L CH4 (g CODremoved)-1 in R1 and R2. The mean values of pH in the effluents ranged from 6.8 to 8.3 and the mean values of total volatile acids remained below 200 mg L-1 in the effluent of R3. The concentrations of total phenols of the affluent ranged from 45 to 278 mg L-1, and the mean removal efficiency was of 52%. The start-up of the anaerobic treatment system occurred after 30 days of operation as a result of inoculation with anaerobic sludge with active microbiota.

scholarly journals Estimation of the Fuzzy Substructure Model Parameters Using the Mean Power Flow Equation of the Fuzzy Structure

1998 ◽  
Vol 120 (1) ◽  
pp. 279-286 ◽  
Author(s):  
C. Soize
Keyword(s):  
Power Flow ◽  
Optimization Problem ◽  
Energy Analysis ◽  
Flow Equation ◽  
Model Parameters ◽  
Type I ◽  
Mean Power ◽  
Nonlinear Constrained Optimization ◽  
The Mean ◽  
Theoretical Results

This paper presents a theoretical approach for identifying the dimensionless mean coefficient of participating fuzzy mass which is the main unknown parameter of the type I or II fuzzy law previously introduced by the author. This method is based on the use of the associated power flow equation, each power term being identified by using a global statistical energy analysis of the fuzzy structure (master structure with its fuzzy substructures). Identification is then carried out by solving a nonlinear constrained optimization problem. An example is given to illustrate the theoretical results.

scholarly journals The Kaldor–Kalecki stochastic model of business cycle

2011 ◽  
Vol 16 (2) ◽  
pp. 191-205 ◽  
Author(s):  
Gabriela Mircea ◽  
Mihaela Neamt¸u ◽  
Dumitru Opris
Keyword(s):  
Hopf Bifurcation ◽  
Business Cycle ◽  
Stochastic Model ◽  
Local Stability ◽  
Mean Values ◽  
Numerical Examples ◽  
Investment Demand ◽  
The Mean ◽  
Theoretical Results

This paper is concerned with the deterministic and the stochastic delayed Kaldor–Kalecki nonlinear business cycle models of the income. They will take into consideration the investment demand in the form suggested by Rodano. The existence of the Hopf bifurcation is studied and the direction and the local stability of the Hopf bifurcation is also taken into consideration. For the stochastic model, the dynamics of the mean values and the square mean values of the model’s variables are set. Numerical examples are given to illustrate our theoretical results.

Articulatory Behavior Pre and Post Full-Mouth Tooth Extraction and Alveoloplasty

1980 ◽  
Vol 23 (3) ◽  
pp. 630-645 ◽  
Author(s):  
Gerald Zimmermann ◽  
J.A. Scott Kelso ◽  
Larry Lander
Keyword(s):  
Control Subject ◽  
High Speed ◽  
Tooth Extraction ◽  
Kinematic Parameters ◽  
Experimental Conditions ◽  
Mean Values ◽  
Articulatory Movements ◽  
The Mean ◽  
Experimental Subjects ◽  
Normal Speech

High speed cinefluorography was used to track articulatory movements preceding and following full-mouth tooth extraction and alveoloplasty in two subjects. Films also were made of a control subject on two separate days. The purpose of the study was to determine the effects of dramatically altering the structural dimensions of the oral cavity on the kinematic parameters of speech. The results showed that the experimental subjects performed differently pre and postoperatively though the changes were in different directions for the two subjects. Differences in both means and variabilities of kinematic parameters were larger between days for the experimental (operated) subjects than for the control subject. The results for the Control subject also showed significant differences in the mean values of kinematic variables between days though these day-to-day differences could not account for the effects found pre- and postoperatively. The results of the kinematic analysis, particularly the finding that transition time was most stable over the experimental conditions for the operated subjects, are used to speculate about the coordination of normal speech.

Comparative Study of Intranasal, Subcutaneous and Intravenous Administration of Desamino-D-Arginine Vasopressin (DDAVP)

1986 ◽  
Vol 55 (01) ◽  
pp. 108-111 ◽  
Author(s):  
M Köhler ◽  
P Hellstern ◽  
C Miyashita ◽  
G von Blohn ◽  
E Wenzel
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Factor Xii ◽  
Additional Advantage ◽  
Mean Values ◽  
Routes Of Administration ◽  
The Mean ◽  
Von Willebrand ◽  
Willebrand Factor ◽  
Factor Antigen

SummaryThis study was performed to evaluate the influence of different routes of administration on the efficacy of DDAVP treatment. Ten healthy volunteers received DDAVP intranasally (i.n.), subcutaneously (s.c.) and intravenously (i.v.) in a randomized cross-over trial. Factor XII and high molecular weight (HMW)-kininogen levels increased only slightly after DDAVP administration. The mean increase of factor VIII: C was 3.1 (i. v.), 2.3 (s. c.), and 1.3 (i.n.) - fold over baseline. Ristocetin cofactor (von Willebrand factor antigen) increased 3.1 (2.5), 2.0 (2.3) and 1.2 (1.2) - fold over baseline mean values after i.v., s.c. and i.n. DDAVP, respectively. The half-disappearance time of factor VIII and von Willebrand factor (vWF) after DDAVP ranged from five (factor VIII: C) to eight hours (vWF). The mean increase of fibrinolytic activity was more pronounced after i.v. DDAVP. The antidiuretic effect was moderate with no apparent differences between the routes of application. This study provides further evidence that both i.v. and s.c. DDAVP administration result in an appropriate and reliable stimulation of haemostasis. An additional advantage of s. c. administration is its suitability for home treatment.

Comparative Study of effectiveness of mobilization with movement (MWM) and End range mobilization (ERM) techniques in frozen shoulder

2018 ◽  
Vol 4 (4) ◽  
pp. 519-522
Author(s):  
Jeyakumar S ◽  
Jagatheesan Alagesan ◽  
T.S. Muthukumar
Keyword(s):  
Range Of Motion ◽  
Frozen Shoulder ◽  
Type I ◽  
Mean Values ◽  
Functional Activities ◽  
Group A ◽  
The Mean ◽  
Group B

Background: Frozen shoulder is disorder of the connective tissue that limits the normal Range of motion of the shoulder in diabetes, frozen shoulder is thought to be caused by changes to the collagen in the shoulder joint as a result of long term Hypoglycemia. Mobilization is a therapeutic movement of the joint. The goal is to restore normal joint motion and rhythm. The use of mobilization with movement for peripheral joints was developed by mulligan. This technique combines a sustained application of manual technique “gliding” force to the joint with concurrent physiologic motion of joint, either actively or passively. This study aims to find out the effects of mobilization with movement and end range mobilization in frozen shoulder in Type I diabetics. Materials and Methods: 30 subjects both male and female, suffering with shoulder pain and clinically diagnosed with frozen shoulder was recruited for the study and divided into two groups with 15 patients each based on convenient sampling method. Group A patients received mobilization with movement and Group B patients received end range mobilization for three weeks. The outcome measurements were SPADI, Functional hand to back scale, abduction range of motion using goniometer and VAS. Results: The mean values of all parameters showed significant differences in group A as compared to group B in terms of decreased pain, increased abduction range and other outcome measures. Conclusion: Based on the results it has been concluded that treating the type 1 diabetic patient with frozen shoulder, mobilization with movement exercise shows better results than end range mobilization in reducing pain and increase functional activities and mobility in frozen shoulder.

A COMPARISON OF TWO METHODS FOR MEASUREMENT OF ALDOSTERONE SECRETION RATE IN MAN

1966 ◽  
Vol 53 (2) ◽  
pp. 177-188 ◽  
Author(s):  
P. Lund-Johansen ◽  
T. Thorsen ◽  
K. F. Støa
Keyword(s):  
Urinary Excretion ◽  
Normal Subjects ◽  
Secretion Rate ◽  
Aldosterone Secretion ◽  
Simple Method ◽  
Mean Values ◽  
Pathological Conditions ◽  
Significant Difference ◽  
Derivative Method ◽  
The Mean

ABSTRACT A comparison has been made between (A), a relatively simple method for the measurement of aldosterone secretion rate, based on paper chromatography and direct densitometry of the aldosterone spot and (B) a more elaborate isotope derivative method. The mean secretion rate in 9 normal subjects was 112 ± 26 μg per 24 hours (method A) and 135 ± 35 μg per 24 hours (method B). The »secretion rate« in one adrenalectomized subject after the intravenous injection of 250 μg of aldosterone was 230 μg per 24 hours (method A) and 294 μg per 24 hours (method B). There was no significant difference in the mean values, and correlation between the two methods was good (r = 0.80). It is concluded that the densitometric method is suitable for clinical purposes as well as research, being more rapid and less expensive than the isotope derivative method. Method A also measures the urinary excretion of the aldosterone 3-oxo-conjugate, which is of interest in many pathological conditions. The densitometric method is obviously the less sensitive and a prerequisite for its use is an aldosterone secretion of 20—30 μg per 24 hours. Lower values are, however, rare in adults.

EFFECT OF OESTRONE-PELLET IMPLANTATION ON PLASMA LEVELS OF PROLACTIN

1970 ◽  
Vol 64 (2) ◽  
pp. 265-272 ◽  
Author(s):  
A. A. van der Gugten ◽  
M. Sala ◽  
H. G. Kwa
Keyword(s):  
Plasma Levels ◽  
Male Rats ◽  
Mean Values ◽  
The Mean ◽  
Dose Levels ◽  
Higher Doses ◽  
Primary Break

ABSTRACT Eight female and eight male rats were castrated at the age of 8 to 10 weeks. Four spayed and four orchidectomized rats received one oestrone/cholesterol pellet (200 μg oestrone) on the day of operation (day 0), a second pellet on day 11 and a third on day 23. The remaining animals received four oestrone/cholesterol pellets at these times. The fluctuations in the prolactin levels in the circulation induced by the oestrogen challenges in these animals were followed during 31 days by radioimmunoassays performed on days 3, 7, 9, 14, 15, 17, 23, 24, 25, 28 and 31. The results suggested that the homoeostatic mechanism regulating plasma levels of prolactin was capable of withstanding the three time-spaced oestrogen challenges only in the spayed animals receiving the lower doses of oestrogen, since it allowed the mean values of the prolactin levels to remain fairly constant during the first 4 weeks. The levels in this group rose to much higher levels only on day 31. The higher doses of oestrone in the spayed rats and both dose levels of oestrone in the orchidectomized animals apparently resulted in a primary break-down of the homoeostatic mechanism, since the prolactin levels in the animals of these groups rose to much higher levels either on day 7 or on day 9. This was followed by a period during which the prolactin levels appeared to be more or less under control, until a second and probably definitive failure of the homoeostatic mechanism allowed the mean levels to rise sharply again.

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