Effects of Surface Concentration on Drying Behavior of Carbohydrate Solutions

As the surface properties of the drying materials are very important not only for the drying rate but also for the quality change during drying, the effects of surface concentration on the drying behavior of liquid foods (sugar solutions) were investigated by isothermal drying experiments and by numerical calculation experiments. The isothermal drying experiments with gelled sugar solution systems (sucrose and maltodextrin) were carried out at various relative humidity (RH) values (RH = 0 to 84%). Separate experiments were carried out for determination of the desorption isotherms.

The isothermal drying curves of sugar solutions at RH = 0 to 51% were very similar. Numerical simulations also showed that the drying curves of these sugars at the surface concentration = 0 and 0.1 are almost the same, although the concentration distributions are different.

When a small amount of gelatin was added to sugar solutions, the drying rate decreased remarkably as the gelatin might form a thin film (skin) near the surface, and consequently the retention of ethanol increased.     

How accurately do drivers evaluate their own driving behavior? An on-road observational study

Self-assessment of driving skills became a noteworthy research subject in traffic psychology, since by knowing one's strenghts and weaknesses, drivers can take an efficient compensatory action to moderate risk and to ensure safety in hazardous environments. The current study aims to investigate drivers’ self-conception of their own driving skills and behavior in relation to expert evaluations of their actual driving, by using naturalistic and systematic observation method during actual on-road driving session and to assess the different aspects of driving via comprehensive scales sensitive to different specific aspects of driving. 19–63 years old male participants (N = 158) attended an on-road driving session lasting approximately 80 min (45 km). During the driving session, drivers’ errors and violations were recorded by an expert observer. At the end of the driving session, observers completed the driver evaluation questionnaire, while drivers completed the driving self-evaluation questionnaire and Driver Behavior Questionnaire (DBQ). Low to moderate correlations between driver and observer evaluations of driving skills and behavior, mainly on errors and violations of speed and traffic lights was found. Furthermore, the robust finding that drivers evaluate their driving performance as better than the expert was replicated. Over-positive appraisal was higher among drivers with higher error/violation score and with the ones that were evaluated by the expert as “unsafe”. We suggest that the traffic environment might be regulated by increasing feedback indicators of errors and violations, which in turn might increase the insight into driving performance. Improving self-awareness by training and feedback sessions might play a key role for reducing the probability of risk in their driving activity.     

Untersuchung der wirkenden Kräfte beim Entstehen und Ablösen von Einzelblasen mit einem Simulationsmodell

Verwendung eines früher entwickelten mathematischen Modells zur Simulierung der Vorgänge bei der Entstehung von Einzelblasen in Flüssigkeiten und Stahl. Berechnung der wirkenden Kräfte und ihrer Anteile.     

Untersuchung der Abhängigkeiten des Ablösevolumens einzelner Gasblasen mit einem Simulationsmodell

Mit einem früher¹) entwickelten, mathematischen Modell zur Simulierung der Vorgänge bei der Entstehung, Ablösung und Bewegung einzelner Blasen, die an Düsen gebildet werden, werden Abhängigkeiten des Ablösevolumens von den Flüssigkeitseigenschaften sowie von konstruktiven und operativen Parametern untersucht. Die Ergebnisse des Simulationsmodells werden mit experimentellen Daten aus dem Schrifttum verglichen. Die Übereinstimmung ist überraschend gut. Als Vorteil des Simulationsmodells stellte sich unter anderem heraus, daß bei der Untersuchung des Einflusses der physikalischen Eigenschaften der flüssigen Phase wie Dichte, Viskosität und Grenzflächenspannung der Einfluß der Veränderung eines einzelnen Parameters unter Konstanthalten aller übrigen untersucht werden konnte, was in Experimenten mit realen Flüssigkeiten nicht möglich ist. Das Blasenablösevolumen steigt (grob gesprochen) mit zunehmender Grenzflächenspannung sowie abnehmender Dichte und ist unabhängig von der dynamischen Viskosität, solange diese unter etwa 100 mPas bleibt. Bei kleinen Laplace-Kostanten ist es unabhängig von der Laplace-Konstanten, erst bei höheren Werten dieser Konstante hängt das Ablösevolumen deutlich von ihr ab. Die Tendenz zur Annäherung an ein Grenzgesetz ist deutlich. Der Düsenquerschnitt hat bei kleinen Gasdurchsätzen großen Einfluß auf das Ablösevolumen, sein Einfluß sinkt mit zunehmendem Gasdurchsatz, bei hohem Gasangebot wächst das Ablösevolumen deutlich mit dem Gasdurchsatz, auch hier ist die Annäherung an ein Grenzgesetz unverkennbar. Kleine Ablösevolumina bedeuten durch die damit verbundene feine Dispergierung des Gases eine große Grenzflächenentfaltung. Maßnahmen zur Erzielung kleiner Ablösevolumina werden angegeben.     

Electronic Nose and Its Applications: A Survey

Machine Intelligence Research - In the last two decades, improvements in materials, sensors and machine learning technologies have led to a rapid extension of electronic nose (EN) related research...     

The Characteristic Parameters of Ni/<Emphasis Type="Italic">n</Emphasis>-6H-SiC Devices Over a Wide Measurement Temperature Range

Ni/n-type 6H-SiC/Ni Schottky barrier diodes (SBDs) have been prepared by the DC magnetron sputtering deposition technique. Their current-voltage characteristics (I-V) have been measured in the measurement temperature range of 40-400 K with steps of 20 K under dark conditions. The barrier height (BH) values from the temperature-dependent forward and reverse bias I-V characteristics by different methods coincide with each other which indicates the elimination of the polarity between the Si and C ions. The ideality factor value remains almost unchanged in the 160-400 K range, and below 160 K, it has the values of 1.57 at 140 K, and 3.82 at 60 K. The BH has the values of 0.79 eV at 400 K, and 0.71 eV at 300 K. The decrease in the BH is due to the fact that the current will preferentially flow through the lowest BH with decreasing temperature due to barrier inhomogeneity. The value of 0.71 eV at 300 K is in close agreement with the values of 0.65 and 0.83 eV reported from the forward bias I-V characteristics for the Ni /n-type 6H-SiC in the literature. Thus, it has been concluded that the reduced barrier devices are promising for applications in devices operating at cryogenic temperatures as infrared detectors, sensors in thermal imaging and small signal zero-bias rectifiers and microwave mixers.     

DYNAMIC ADSORPTION OF S02 ON ZEOLITE MOLECULAR SIEVES†

Sulfur dioxide is one of the major pollutants resulting from fuel combustion. Numerous dry, semi-dry and wet processes have been developed for pollution control of sulfur dioxide. Solid carbonates, natural and synthetic zeolites, ion exchange resins and carbon based sorbents are the most commonly used dry sorbents for sulfur dioxide removal

In this study, measurements of the adsorption properties of sulfur dioxide on zeolites were investigated. The adsorbents used in this work are 5A, 4A and AW300 type molecular sieve zeolites. Adsorption equilibrium parameters were determined from the pulse chromatographic response to injections of low concentrations of sulfur dioxide. The method of moments were used to evaluate the adsorption equilibrium parameters from pulse chromatographic experiments. Data, such as adsorption equilibrium constants or reaction rate parameters are essential in the design of adsorption systems or reactors in which sulfur dioxide is removed

The experiments were conducted in a temperature range of 523-718 K. The relatively strong adsorption properties of sulfur dioxide on zeolites necessitated the use of high carrier gas flow rates and subsequently non-isobaric operation. Non-isobaric pulse chromatography theory was found to describe accurately the adsorption trends." printpubdate="Adsorption equilibrium constants of S0₂ were found to decrease considerably with increasing temperature. It was also found out that adsorption of SO₂ on the adsorbents investigated were found to decrease in the order of AW300 ≤ 4A ≤ 5A. The adsorption equilibrium parameter of S0₂ on 5A was found as 11.78 at 673 K, whereas it has a value of 157.11 at 523 K. The adsorption equilibrium parameter of S0₂ on 4A zeolite was determined to be 8.63 at 718 K and 213.78 at 523 K.     

Computer simulation on the hydrodynamics of gas injection process in liquid steel

It is shown that with the aid of digital simulation methods complex multiphase interrelated systems, such as gas-injection process can be analysed. Interdependencies can be revealed and quantitative evaluation of characteristic system quantities are provided. The method of digital system simulation is a very convenient tool for process analysis or system engineering. Results of the computer-aided process simulations (Caps) yield a better understanding of complex phenomena and better aimed engineering of gas dispersion techniques in metallurgical processes. A particular interest of this investigation is to reveal the effect of mass-transfer rate on the hydrodynamic behaviour of a gas-injection process. The combined effects of total flow rate of injected gas and mass-transfer rate on the system quantities such as mixing power, induced liquid flow rate, holdup, interfacial area and volumetric mass transfer coefficient are evaluated under steady state conditions of the investigated systems and illustrated in simulation plots. The liquid velocity has a minor effect on bubble size at some distance from the orifice but controls the location of bubble breakup. The frequency of bubble breakup and final bubble size depends on the intensity of mass transfer. Mixing power due to gas bubbles and circulation velocity of the steel bath increase appreaciably if there is a chance of bath reactions producing more gas. The integral mean values of mixing power, induced velocity of liquid and holdup in plume, specific interfacial area and volumetric mass-transfer coefficient increase with increasing total flow rate of injected gas and intensity of mass transfer.