فايل هاي درسي

چكيده : 

Some thermal decomposition reactions display self-inhibiting behaviour, where the produced gas negatively

influences the reaction progress. Further, a build-up of internal pressure caused by the product gas

may alter the reaction pathway in a way that favours one pathway over others. Two well-known cases of

this kind of reaction are the thermal decomposition of limestone and gibbsite, in which carbon dioxide

and water vapour are the produced gases, respectively. A multi-stage, multi-reaction, shrinking core

model is proposed for the simulation of this type of process. The model emphasises the role of the produced

gas, not only in mass transfer, but also in the reaction kinetics. It includes parallel and series reactions,

allowing for the formation of an intermediate species. The model has been applied to the

conversion of gibbsite to alumina, including the formation of intermediate boehmite. Modelling results

for gibbsite conversion, boehmite formation and its subsequent consumption, as well as alumina formation,

agree well with literature data; the corresponding kinetic parameters are estimated for all reactions.

Significantly, the experimentally-observed plateaux in the particle’s temperature history are predicted by

the model. The role of heating rate and particle size on boehmite formation is also evaluated using the

model, and is in agreement with observation.

چكيده : 

This paper intends to gain insight into the role of childhood relationships and experiences

within the parental home for the formation and meaning of later family relationships and

loneliness. Particularly, childhood attachment to mother and father and stressful

childhood experiences were studied in their association with satisfaction in the romantic

relationship, the quality of adult family ties and the perceived quality of the social

network, i.e. loneliness in adulthood. Based on data from the Netherlands Kinship Panel

Study () structural equation models were estimated to predict adult relationships

and loneliness with childhood experiences. Positive attachment experiences with parents,

such as reliability, closeness and supportiveness during childhood were associated with

greater satisfaction in the romantic relationship, stronger family ties and less loneliness,

whereas stressful childhood experiences, such as conflicts and violence negatively

predicted the quality of adult relationships. Life span theoretical perspectives, such as

attachment theory are discussed as useful unifying framework to study social relation-

ships, their interconnectedness and association with outcome during all phases of life.

چكيده :

We address the problem of computing the exact characteristics of any subsegment of a Digital Straight Line (DSL) with known characteristics (a slope ab, a shift to origin μ). We present here two new algorithms that solve this problem, whose correctnesses are fully proved. Their principle is to descend/climb the Stern–Brocot tree of fractions in a topdown/
bottom-up way. The top-down algorithm SmartDSS has a time complexity which depends on the sum of the quotients of the continued fraction of the output slope and on the number of pattern repetitions. As a corollary, its time complexity is bounded by the sum of the quotients of the continued fraction of the input slope, Said and Lachaud (2009) [18]. The bottom-up algorithm ReversedSmartDSS has a time complexity proportional to the difference of depth of the input slope and the slope of the output segment, Said and Lachaud (2011) [17]. As a corollary, its complexity is thus logarithmic in the coefficients of the input slope. These algorithms are also efficient in practice, as shown by a series of experiments comparing these new  lgorithms with standard arithmetic digital straight segment recognition.

چكيده : 

The majority of titanium based bone-level dental implants available on the market today feature a

sand-blasted and acid-etched (SBAE) surface that contains comparably high hydrogen levels. Cathodic

polarization of titanium in acidic solutions is known to further increase titanium hydride on the

surface. The aim of this study was to explore the effect of cathodic reduction on titanium (Ti) and

titanium–zirconium (TiZr) with a SBAE surface in order to investigate the potential of such a process for

further improving surfaces for bone anchored dental implants. Samples of both materials were cathodically

polarized in acidic solution at different current densities and for different process times. Chemical

analysis of the hydrogen levels by SIMS showed that cathodic reduction re-arranged the hydride already

present on the surfaces from the etching process but could not significantly increase hydride levels. The

hydrogen layer created by the preceding hot acid etching appeared to modulate further hydride creation.

Analysis of the surface topography by SEM showed changes to the nano-topography of both materials

after polarization. TiZr showed homogeneously distributed nano-spheres as they were already observed

for TiZr SBAE at increased size of 80–100 nm on the whole surface. By contrast, polarization of Ti created

nano-nodules and nano-spheres of 150–200 nm on the surface. These spheres were interconnected to

form flower-like structures along the ridges and peaks of the surface. Moreover the flanks were covered

by a rippled structure of isotropically distributed small-diameter (10–20 nm) nano-nodules.

چكيده : 

The crystallographic properties of tantalum films deposited as a bioactive coating on Co–Cr–Mo and

Ti–Al–Nb alloys have been investigated. The desired tough and ductile alpha phase of tantalum has

been obtained by DC magnetron sputtering on Co–Cr–Mo and Ti–Al–Nb substrates. The thickness of the

tantalum layer was between 20 and 600 nm. The crystallographic structure of tantalum thin film was

dependent on the sputtering parameters such as DC power, bias voltage and gas impurities. Oxygen

is an important factor for the stabilization of the tantalum alpha phase on Co–Cr–Mo substrate. The

crystallographic structure and texture of tantalum thin films was found to be additionally dependent on

the substrate composition. For Ti–Al–Nb substrate, oxygen content was not an important factor for the

stabilization of the alpha phase. The observed shift of X-ray diffraction peaks to lower 2() is an indication

of stress evolving during the sputtering process and was dependent on bias voltage and oxygen content

of the carrier gas.

چكيده : 

Weprovethateveryfinitesetofhomotheticcopiesofagivenconvexbodyintheplanecanbecoloredwithfourcolorssothatanypointcoveredbyatleasttwocopiesiscoveredbytwocopieswithdistinctcolors.ThisgeneralizesapreviousresultfromSmorodinsky(SIAMJ.Disc.Math.2007).Thenweshowthatforanyk2,everythree-dimensionalhypergraphcanbecoloredwith6(k−1)colorssothateveryhyperedgeecontainsmin{|e|,k}verticeswithmutuallydistinctcolors.ThisrefinesapreviousresultfromAloupisetal.(Disc.&Comp.Geom.2009).Ascorollaries,weimproveonpreviousresultsforconflict-freecoloring,k-strongconflict-freecoloring,andchoosability.P

چكيده : 

In this paper, the solution of nonsmooth equations is studied. We first transform the

problem into an equivalent nonsmooth optimization problem and then the quasisecant

method is introduced to solve it. Some nonsmooth equations that have arisen from bilevel

programming problems are solved by our proposed method. The numerical results show

the effectiveness and efficiency of our proposed method.