PCCP_2009_11_1397_Stability of formate species on b-Ga2O3
Stability of formate species on b -Ga 2O 3
M.Calatayud,*a S.E.Collins,b M.A.Baltana
s b and A.L.Bonivardi b Received 10th January 2008,Accepted 25th November 2008
First published as an Advance Article on the web 19th January 2009DOI:10.1039/b800519b
Gallia (gallium oxide)has been proved to enhance the performance of metal catalysts in a variety of catalytic reactions involving methanol,CO and H 2.The presence of formate species as key intermediates in some of these reactions has been reported,although their role is still a matter of debate.In this work,a combined theoretical and experimental approach has been carried out in order to characterize the formation of such formate species over the gallium oxide surface.
Infrared spectroscopy experiments of CO adsorption over H 2(or D 2)pretreated b -Ga 2O 3revealed the formation of several formate species.The b -Ga 2O 3(100)surface was modelled by means of periodic DFT calculations.The stability of said species and their vibrational mode assignments are discussed together with the formate interconversion barriers.A possible mechanism is proposed based on the experimental and theoretical results:?rst CO inserts into surface
(monocoordinate)hydroxyl groups leading to monocoordinate formate;this species might evolve to the thermodynamically most stable dicoordinate formate,or might transfer hydrogen to the surface oxidizing to CO 2creating an oxygen vacancy and a hydride group.The barrier for the ?rst step,CO insertion,is calculated to be signi?cantly higher than that of the monocoordinate formate conversion steps.Monocoordinate formates are thus short-lived intermediates playing a key role in the CO oxidation reaction,while bidentate formates are mainly spectators.
Introduction
Hydrogen production for energy-related purposes is a major task in catalysis nowadays.One of the most promising processes for hydrogen production is steam reforming from methanol (SRM):CH 3OH +H 2O -3H 2+CO 2.1,2However,methanol decomposition occurs alongside with the main reaction and it is responsible for the production of CO in the system.
Both the SRM reaction and its reverse,methanol synthesis from H 2and CO 2,can be e?ciently accomplished over palladium–gallium oxide (gallia)-based catalysts.3,4
The mechanisms for methanol decomposition and methanol production from CO 2have been studied by some of us.5,6The key intermediate in these two reactions was proposed to be the formate surface species (HCOO à),which can be either decom-posed to carbonate and Ga–H to ?nally desorb as CO 2and H 2,or be hydrogenated stepwise to methylenebisoxy,methoxy and methanol.5,6It was suggested as well that the presence of gallium oxide also favours the reverse WGS (water gas shift)reaction (CO +H 2O -CO 2+H 2)via formate intermediates.7
However,several formate species coexist or can be formed under reaction conditions,and some of them su?er inter-conversion.5The role of formate species as potential reaction intermediates in the WGS reaction has been the subject of a renewed debate in the recent literature.The main work has
been focused on noble metal catalysts supported on ceria.Two main reaction mechanisms have been proposed for the WGS reaction over these ceria-based materials:8,9(i)a redox mechanism,where CO(g)adsorbs on metal sites to form a carbonyl species,which then reacts with an oxygen atom coming from the ceria to form CO 2(the reduced ceria is subsequently reoxidized by water and hydrogen is produced as a result),as follows:
CO +O Lattice -CO 2+&(&:oxygen vacancy)&+H 2O -H 2+O Lattice ;
and (ii)a non-redox mechanism,where it was concluded that the main reaction intermediate is a bidentate formate produced by reaction of CO with terminal hydroxyl groups on the ceria surface (this formate species was thought to decompose into H 2(g)and CO 2(g)via surface carbonate groups),as summarized in the following steps:
CO +OH -HCOO
HCOO -12H 2+CO 2+&H 2O +&-OH +12H 2.
Based on DRIFTS analyses combined with the utilization of
isotopic tracers,Meunier’s group showed,on a Pt/CeO 2catalyst,that formates were less reactive than carbonyl and carbonate species under steady-state conditions.8More recently,the same research group concluded,from the analysis of the formate exchange curves between 428and 493K,that at least two levels of reactivity were present.10,11‘‘Slow formates’’displayed an exchange rate 10-to 20-fold slower than that of
a
Laboratoire de Chimie The ′orique,UMR 7616CNRS,Bo??t e 137site Ivry,Universite ′Pierre et Marie Curie,4Place Jussieu Paris,75252cedex 05,France.E-mail:calatayu@lct.jussieu.fr;Fax:+33(1)44274117;Tel:+33(1)44272682b
Instituto de Desarrollo Tecnolo
′gico para la Industria Qu?′m ica (CONICET,UNL),Gu ¨emes 3450,3000Santa Fe,Argentina
PAPER https://www.wendangku.net/doc/872119626.html,/pccp |Physical Chemistry Chemical Physics
P u b l i s h e d o n 19 J a n u a r y 2009. D o w n l o a d e d b y F u d a n U n i v e r s i t y o n 02/09/2013 15:10:01.
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the reaction product,CO 2,and ‘‘fast formates’’which were exchanged on a time scale similar to that of CO 2.However,a discussion taking into consideration the presence of di?erent types of surface formate groups is so far absent in those pictures.
Thus,it seems clear that many aspects regarding the structure and reactivity of formates are still not well under-stood,in particular their role as intermediates,or spectators,in the WGS reaction.For this reason we have performed a combined theoretical and experimental investigation of the stability of formate species on the pure Ga 2O 3surface.We have focused on the characterization of the adsorption mode and the relative stability of the di?erent types of formates obtained from the reaction:CO +O Lattice H à-HCOO à.A possible mechanism for formates interconversion and oxidation to CO 2is proposed based on the experimental ?ndings and the calculated reaction barriers.
Methodology
Computational details
The Perdew–Burke–Ernzerhof functional has been used to compute total energy calculations as implemented in the VASP code.12,13The core electrons are kept frozen and replaced by projector augmented wave generated (PAW)pseudopotentials while the valence electrons are described with a plane-wave basis set (cuto?=400eV).The valence electrons explicitly treated are the following O:s 2p 4,Ga:s 2p 1,C:s 2p 2,H:s 1.A 3?3?1Monkhorst–Pack sampling in the Brillouin zone is used;this scheme gives converged total energies within 0.010eV,and surface energies within 0.005J m à2.Geometry optimizations are carried out with the conjugate-gradient algorithm.Harmonic frequencies were calculated with the ?nite di?erences method as implemented in VASP;the structures are checked to be minima in the potential energy hypersurface.The reaction barriers for interconversion of di?erent species are determined by constrained optimiza-tion algorithms (nudged elastic band,NEB)as implemented in the code.14
The (100)surface is thermodynamically the most stable plane of the b -Ga 2O 3crystal structure;15it has been modelled by a slab containing 4Ga 2O 3layers (see Fig.1).The surface is terminated by tetrahedral Ga t ,uncoordinated octahedral Ga cus ,and three-fold oxygen O 3f atoms.A 2?1unit cell is
employed,with dimensions 6.00?5.75?20A
3,leaving a vacuum layer of B 10A
between successive slabs.For the structure characterization all the atoms are allowed to relax;for the transition states only the uppermost 2Ga 2O 3layers together with the adsorbate are allowed to relax.The surface is terminated by tetrahedral Ga t ,coordinatively unsaturated octahedral Ga cus ,and three-fold oxygen O 3f atoms.Experimental details
b -Ga 2O 3phase,with a Brunauer–Emmett–Teller surface area equal to 64m 2g à1,was synthesized following the procedure previously reported by some of us.16A self-supported wafer of the gallia sample was placed into an infrared Pyrex s cell with water-cooled NaCl windows,which was attached to a
conventional manifold system.After an in situ cleaning pre-treatment of the wafer (heating under O 2up to 723K),the sample was activated at 723K by ?owing H 2(or D 2)through the cell at atmospheric pressure,then cooling down to 298K under vacuum.Next,pure CO (100cm 3min à1)was admitted into the IR cell and the temperature was increased from 298to 723K.All the treatments were done at 0.1MPa.In situ infrared spectra were taken using a Shimadzu 8210FT-IR spectrometer employing a deuterated L -alanine doped tri-glycine sulfate (DLATGS)detector.
Results and discussion
A suitable analysis regarding formate(s)formation on the gallia surface can be done by considering CO adsorption
and
Fig.1The slab model used in the calculations.Coordinatively unsaturated octahedral Ga cus ,tetrahedral Ga t and three-fold oxygen O 3f atoms are exposed on the (100)b -Ga 2O 3surface.
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reactivity.The adsorption of CO on a bare,dehydroxylated Ga 2O 3surface is found to be very weak:it is not detected in experiments and the energy stabilization is calculated to be of 0.02eV.Conversely,formate species are generated by CO insertion on OH surface groups on a wide range of hydroxylated metal oxides (for example,ZnO,Al 2O 3,TiO 2,V 2O 5,Fe 2O 3,ZrO 2and CeO 216–19).The formation and de-composition of HCOO àspecies on gallium oxide proceeds as shown in the following
scheme:
The ?rst step involves the insertion of CO in the OH bond leading to the formation of a formate species.This reaction proceeds without electron transfer and needs the presence of a hydroxyl group.Subsequent steps involve the oxidation to CO 2and its desorption,leaving an oxygen vacancy on the surface.
We have focused on the characterization of the formate species coming from the CO insertion in the OH group.The presence of hydride and hydroxyl groups has been detected in IR experiments after H 2adsorption.20Such pairs H à/H +are stabilized on irreducible metal oxide surfaces (MgO,ZnO),at variance to reducible transition metal oxides (TiO 2,V 2O 5)where no hydride but only hydroxyl groups are found after hydrogenation.21,22Computational modelling
The system considering formal adsorption of H 2as H à/Ga cus +H +/O 3f has been modelled.The calculated adsorption energy is à2.25eV,indicating an exothermic process with respect to atomic hydrogen.At this stage we did not consider terminal or bridging hydroxyl groups that can be originated at defects or through a di?erent mechanism.The 2?1unit cell is shown in Fig.2:it contains two Ga cus ,one of them capped by a H atom,and a O 3f –H group,together with Ga cus and O 3f available for reactivity.
Carbon monoxide insertion in the OH bond was considered,leading to four formate structures which are shown in Fig.3.The insertion of CO in the OH bond is exothermic for all the structures.The most stable system is II,which corresponds to a dicoordinate formate,stabilized by the formation of two Ga–O bonds.The adsorption energy with respect to CO and the hydrogenated surface is à0.82eV.Structure IV is 0.32eV less stable in energy;it corresponds to the insertion of CO into the lattice O 3f –H group.Structure I is a monodentate formate that could be formed by rearrangement of structure IV:the lattice oxygen is abstracted and the hydride tilts to occupy the vacancy.Structure III involves a dicoordinate formate bonded to one gallium site;it is 0.47eV less favourable than the dicoordinate formate II and evolves to the latter upon opti-mization.Note that a hydride species is always present in the models,in some cases occupying a lattice oxygen vacancy
(I,II and III).The barriers for the interconversion of such formate species are calculated and discussed below.
The harmonic frequencies calculated for the four structures are reported in Table 1(see next section for experimental data).The calculation of intensities is not implemented in the code.The formate stretching modes are located around 1600cm à1(COO asymmetric)and 1300cm à1(COO symmetric).The vibrations around 3000cm à1and 1300cm à1are assigned to the C–H stretching and bending modes,respectively.Hydride groups (Ga–H)are found to vibrate at values of 1900cm à1,that is at 100cm à1lower than the experimental value (B 2000cm à1),20which is found for metal-H frequencies calculated by DFT.23Infrared spectroscopy
Because the spectra in the hydroxyl IR region (3700–3000cm à1)were opaque,by the interference of gaseous water from the environment (i.e.outside the IR cell),the Fig.4shows the infrared spectra during the temperature-programmed adsorp-tion of CO (101.3kPa)on b -Ga 2O 3previously activated under molecular deuterium.The IR spectra show that,as the intensity of the OD bands (at 2800–2600cm à1)decreased from 448K,new overlapped bands developed in the 1700–1300cm à1region.The same spectroscopic
behaviour
Fig.2Hydrogenated slab model.After H 2adsorption Ga–H and
O–H groups are formed.Undercoordinated Ga cus and three-fold oxygen O 3f atoms are exposed,Ga o stands for a H-capped Ga cus .
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was observed over the hydrogen-activated b -Ga 2O 3(that is,gallium oxide activated under H 2)upon due consideration,
vis-a
-vis the isotopic shifting of the respective bands.A detail of the IR spectra at 623K,that is at the highest total surface formate concentration (mainly type II and III formates,see below),together with the partial assignments of the vibra-tional modes of HCOO à(DCOO à)and Ga–H (Ga–D)groups on the gallia surface are shown in Fig.5.
The position and relative intensity of the new set of bands in the 1700–1300cm à1region refers to formate groups as follows:the most intense bands at approximately 1600and 1330cm à1
correspond to the asymmetric and symmetric stretching mode of the COO group [n as (COO)and n s (COO),respectively],of the HCOO àspecies.5It is clear that these bands shifted no more than à30cm à1for the deuterated formate species (Fig.5).5Meanwhile,the bending mode of the CH group [d (CH)],which showed up at approximately 1360cm à1,was strongly a?ected by the isotopic exchange and shifted to 993cm à1(not shown),that is,by a factor of 1.37,in agreement with the expected theoretical ratio of 1.36[d (CH)/d (CD)=(m CD /m CH )1/2,where m CD and m CH are the reduced masses of CD and CH,respectively].5Simultaneously,two weak
bands
Fig.3Di?erent formate groups calculated over the b -Ga 2O 3(100)surface:mono-(I),di-(II and III),and tri-coordinate (IV)species.Between parentheses,the relative energy with respect to CO +Ga 2O 3–H 2,in eV;latt stands for lattice oxygen.Table 1
Calculated and experimental harmonic frequencies for the formate (HCOO à)species
Vibrational mode Infrared frequencies of formate species/cm à1I
II
III IV Calcd Exptl a Calcd Exptl a Calcd Exptl a Calcd Exptl a C–H stretching
2923291029732915301128953062n.d.COO asym stretching (n as )1634166515381580158116001624n.d.C–H bending
1341135013541385125013551294n.d.COO sym stretching (n s )1252130513101369132413321187n.d.D n =n as àn s
382
360
228
211
257
268
437
—
a
Average values obtained from the whole set of IR spectra between 448and 723K,during the temperature-programmed adsorption of pure CO (100cm 3min à1,0.1MPa)over a b -Ga 2O 3sample previously activated in H 2(see the experimental section for operational details).n.d.:not detected.
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assigned to the n (CH)[B 2900cm à1]and the combination of the n as (COO)+d (CH)modes,were also noticeable in the spectrum obtained at high surface formate concentration (see Fig.5).Yet,the isotopic shifting in this last two cases could not be measured under the temperature programmed CO adsorption experiments because of the very low intensity of the n as (COO)+d (CD)signal,and the overlapping between the n (CD)peak and the n (CO)band of DCOO àand gaseous CO,respectively.
It should be notice that (bi)carbonate species were not detected under our experimental conditions.In a deep infrared study of the carbon dioxide adsorption of di?erent gallium
oxide polymorphs,some of us have shown that (bi)carbonate
groups develop several bands in the 1800–1200cm à1region.24However,those (bi)carbonates were really unstable,that is,only polydentate carbonates are still present under vacuum (base pressure =10à6Torr)but they decompose under heating (4373K).Moreover,carbonate groups (CO 32à)should not show any isotopic shifting after reacting CO with OD surface species,because no hydrogen (or deuterium)bond is involved on CO 32à.Thus,this is a further piece of evidence that the bands observed in the 1700–1300cm à1region do not belong to carbonate groups.
Then,it is evident that more than one peak for each infrared mode of formate are present in the spectra,which means that HCOO àgroups with di?erent coordination coexist on the gallia surface.Certainly,the distinction among these di?erent surface coordination formate species is not an easy task owing to the IR signal overlapping.Fig.6shows a correlation chart,which was built by compiling the experimental IR signals of di?erent formate species over several metal oxides and organo-metallic complexes.16–18,25–41According to Busca and Lorenzelli,17formate species can be distinguished from each other by the band splitting of the asymmetric and symmetric COO stretching modes [D n (COO)=n as (COO)àn s (COO)].After comparing the frequency location of the n as (COO)and n s (COO)of formate metallic complexes whose structures were determined by X-ray di?raction,it was possible to establish the following D n (COO)progression for the monodentate (type I),bidentate (type III)and bridged (type II)formate species,respectively:type I 4type III Z type II.17In our case,and computing the D n (COO)from average n (COO)values,this last trend is identical:291cm à1(type I)4223cm à
1
Fig.4Thermal evolution of the IR spectra during the CO adsorption (760Torr CO)over a b -Ga 2O 3surface activated under D 2at 723K.(Background subtraction:clean wafer at each temperature,under
vacuum.)
Fig.5IR spectra of adsorbed HCOO à(DCOO à)and Ga–H (Ga–D)groups on b -Ga 2O 3activated in H 2(A)or D 2(B),upon CO adsorption (760Torr CO)at 623K.
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(type III)4208cm à1(type II).However,the range of positions of the n as (COO)and n s (COO)bands for all of these three types of formate are overlapped (see Fig.6),and a clear-cut discernment among them is very di?cult from experimental data alone (that is,by merely comparing reported experimental band positions and/or performing isotopic exchange experiments).Even more,some of us have mis-interpreted the bidentate formate IR signal in the past.5,6The theoretical calculation of the vibrational frequencies by DFT presented here sheds additional light on the assignment of formate species.Thence,the calculation makes it possible to discriminate among type I,II and III formates on gallium oxide,as presented on Table 1.
The di?erent surface formate species (mainly,types II and III,and traces of type I)reached a maximum at approximately 573K (see Fig.4),where a band attributed to the Ga–D stretching mode showed up [n (Ga–D)=1430cm à1]20and increased its intensity up to 698K.However:(i)type I species could only be detected in a short range of temperature (573–598K),and (ii)at the highest temperature,that is 723K,only the type II formate species remains over the gallia surface.
At 623K type I formate is no longer detected and (assuming similar extinction coe?cients)a much smaller amount of formate III is still present,as compared to the type II species (see Fig.5).That is,similar stability of type I and III formates is observed,being the formate II the most stable species.The inset in Fig.5displays—after subtracting the intense band of gaseous CO—the Ga–H stretching signal at approximately 2000cm à1,in accordance with previous results.20The experi-mental ratio of the n (Ga–H)/n (Ga–D)frequencies was equal to 1.39,in agreement with the expected theoretical ratio of 1.40for the H–D isotopic exchange of Ga–H species.20
Therefore,these results suggest that CO reacts with the surface OH groups towards formate species with di?erent thermal stability,being the dicoordinate (type II)formate the most stable oxycarbonaceous species.So,in an e?ort to improve the picture about the coexistence and the band assignment of the di?erent types of formate species,an extra IR experiment was run by feeding the IR cell with a ?owing
mixture of CO 2and H 2(H 2/CO 2=3,140cm 3min à1)at 0.1MPa,that is,under reverse water gas shift reaction conditions (CO 2+H 2=CO +H 2O).The b -gallia sample was activated under O 2and H 2,as previously described in the experimental section.Next,the temperature-programmed reverse WGS reaction was studied over the b -gallium oxide wafer using H 2/CO 2=3.Under these experimental conditions the best signal-to-noise ratio for the monodentate formate was achieved at 573K.Fig.7shows the IR spectrum of the formate region and the complete assignment of the vibrational modes of type I,II and III formates only in one spectrum (spectrum A).For comparison purposes spectrum B,corresponding to the CO adsorption on gallia at the same temperature,is also included.
It is reasonable to conclude,then,that the measured IR frequencies for the di?erent formate species are in
good
Fig.6Experimental IR vibrational frequency correlation chart of di?erent types of formate species over several metal oxides and organometallic complexes [comb1stands for n as (COO)+d (CH)and comb2stands for n s (COO)+d (CH)].The compiled data correspond to monodentate (type I),bridged (type II)and bidentate (type III)formate species.17–19,23–39The light-grey regions indicate the range for the reported vibrational frequencies,while the dark-grey regions correspond to the overlapping between two neighbour light-grey regions,that is,between two vibrational modes of the same type of
formate.
Fig.7IR spectra of formate species I,II,and III at 573K on b -Ga 2O 3(activated in H 2at 723K):(A)under a ?owing mixture of hydrogen and carbon dioxide (H 2/CO 2=3,140cm 3min à1;0.1MPa);(B)upon CO adsorption (760Torr CO).
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agreement with those predicted by the DFT calculations (Table 1).
Nevertheless,no experimental evidence for the tricoordinate (type IV)formate was found under any of the experimental conditions employed here,which con?rms that formate IV is the most unstable species on the gallia surface.
Truly,some reaction intermediates are usually di?cult to be found due to their low concentration,low stability and/or high reactivity,while spectators (namely,stable and/or not active species)are frequently observed instead,and sometimes erroneously assumed as true reaction intermediates.42,43As a consequence,relevant catalytic and kinetic information may escape spectral ‘capture’,and inappropriate spectral inter-pretation might be conducive to de?cient reaction pathways.In our case,for instance (and to circumvent this frequent hurdle),it is apparent that the evolution of surface formate species must be followed by using the IR signals in the 1700–1300cm à1region instead of the C–H stretching region,where no distinction among formate groups can be performed whatsoever.
Formate interconversion
The barriers for the interconversion of the di?erent formate species have been calculated.A reaction path connecting the di?erent structures has been constructed for the hydrogenated model,and is shown in Fig.8.
The ?rst step is the CO insertion into the surface OH group leading to the three-fold coordinated formate (species IV).The barrier calculated for the corresponding transition state is 2.11eV.Next,the formate evolves to monocoordinated (species I)by the abstraction of lattice oxygen,the vacancy being ?lled by the hydride group.The H atom is now closer to the Ga t site,leaving a Ga cus .The barrier for this process is 0.77eV.Structure I could then rotate and form any of the
dicoordinated formates II (bridged)or III (bidentate).We were not able to ?nd a saddle point for such processes;if it existed it would be (in either case)lower in energy than the other barriers involving breaking/forming bonds.Mono-coordinated formate could then oxidize to CO 2by an H-transfer to a lattice oxygen.
The calculated barrier of 2.11eV found for the CO insertion into the surface OH group is indeed very high.This might be due to the coordination of the surface hydroxyl group,which is three-fold in the model used.For the sake of completeness we have calculated the barriers in a model containing a monodentate hydroxyl group.The model used is equivalent to the hydrogenated model (Fig.2)where the hydride group is replaced by an OH group,which is formally a water molecule dissociated as OH à/Ga cus +H +/O 3f .The corresponding reaction paths and energy diagrams are displayed in Fig.9.The energy barrier for the CO insertion into this singly coordinated hydroxyl group is 1.78eV,which is signi?cantly lower than the value obtained for the three-fold coordinated one.This indicates that the CO insertion process takes place on the terminal hydroxyl groups rather than on the many-fold coordinated.The so-formed monocoordinate formate,I-bis,is stabilized by a hydrogen bond to the surface.The subsequent conversion to the most stable dicoordinate formate II-bis takes place through a barrier of 0.54eV.We have also calculated the barrier for the oxidation of the monocoordinate formate to CO 2,which is 0.87eV.This process occurs via the hydrogen transfer to a surface gallium site forming a hydride group and a surface oxygen vacancy.
According to these results,the rate-limiting step is the insertion of CO in the surface hydroxyl group.The high barrier explains the absence of reaction between CO and
gallia
Fig.8Reaction path for the interconversion of the di?erent formate species (see Fig.3),barriers in eV.Inset:transition state structures,
distances in A
.Hydrogen atoms are indicated with a thick arrow.O latt :lattice oxygen,Ga t :tetrahedral
site.Fig.9Reaction path for the interconversion/decomposition of the di?erent formate species on a monocoordinate hydroxyl-covered surface (HOH–Ga 2O 3),barriers in eV.Inset:transition state struc-tures,distances in A
.O vac :oxygen vacancy.P u b l i s h e d o n 19 J a n u a r y 2009. D o w n l o a d e d b y F u d a n U n i v e r s i t y o n 02/09/2013 15:10:01.
at low temperatures,as it was observed experimentally.Once this barrier is overcome,the evolution to a monodentate formate takes place.Further conversion to dicoordinate formates proceeds with a signi?cantly lower barrier to species III (isoenergetic),and species II and II-bis (the most stable).Infrared experiments indicate the presence of both species II and III,which are accumulated up to high temperatures.The low intensity of the IR bands assigned to species I can be explained by the rapid transformation to the most stable species,type II.Therefore,the monodentate formates are short-lived intermediates due to (i)a high activation energy for their formation and (ii)a lower barrier for intercorversion/decomposition to CO 2.This behaviour has been observed in other metal oxides (see for instance ref.44).
However,type II species disappear at higher temperatures.This might be due to the conversion to species I and sub-sequent oxidation to CO 2.The monocoordinate formate would then be the key reaction intermediate in the CO oxidation while dicoordinated formates would mainly be spectators.The dicoordinate formates II would ultimately be consumed by transformation to monocoordinate I and further oxidation.
Note that the calculated barriers,even considering mono-coordinated surface hydroxyl groups,are high (1.78eV).Experimentally it is observed the formation of formates at 473K,which would correspond to lower barriers.This disagreement might be due to the presence of more reactive hydroxyl groups (as in defects,nests or more reactive surfaces).Also,the calculated values could be overestimated by the DFT method used:it is known that the values of energetic barriers strongly depend on the exchange–correlation functionals employed.Overall,the mechanism proposed,despite the high values found for the CO insertion step,is coherent with the observed data.
Conclusions
The interaction of CO with surface hydroxyl groups leads to the formation of stable formate species as con?rmed by infrared spectroscopy and periodic DFT calculations.The dicoordinate formate bonded to two uncoordinated gallium sites is found to be the most stable species.The corresponding IR vibrations of the formate species have been calculated and compared to experimental assignments with good agreement.A possible mechanism for formate interconversion and oxida-tion to CO 2is proposed based on the experimental data and calculated energetic barriers.The ?rst step consists in the CO insertion into a surface OH group leading to a mono-coordinate formate,with a barrier of 1.78eV for a mono-coordinate hydroxyl species.Next,the monocoordinate formate rotates to form a bidentate formate which is the most stable species.This process is associated to a calculated barrier of 0.54eV.The monodentate formate may also oxidize to CO 2with a hydrogen transfer to a surface gallium site,forming a hydride group and an oxygen vacancy.The calculated barrier for this process is 0.87eV.This mechanism explains the observed trends in IR experiments:formation of formates at 473K (the insertion of CO into hydroxyl groups possesses the highest calculated barrier and is the rate limiting step),type II
formates accumulate (and are assigned to dicoordinate species)at higher temperatures,at 673K the signal disappears (dicoordinate species reconvert to monocoordinate and oxidize to CO 2)and a Ga–H band appears (hydride groups are formed by H-transfer from monocoordinate formate to gallium surface sites).The monocoordinate formate would thus be a short-lived intermediate in the oxidation of CO in agreement with the small signal observed in the IR spectra,while dicoordinate species would be mainly spectators.
Acknowledgements
Computational facilities by IDRIS,CINES and CCRE are acknowledged.SEC,MAB and ALB acknowledge the ?nancial support of the CONICET and ANPCyT of Argentina.
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AutoForm教程
ＡｕｔｏＦｏｒｍ介绍及其应用￣ 当代汽车和现代模具设计制造技术都表明，汽车覆盖件模具的设计制造离不开有效的板成形模拟软件。世界上大的汽车集团，其车身开发与模具制造都要借助于一种或几种板成形模拟软件来提高其成功率和确保模具制造周期，国际上的软件主要有美国ｅｔａ公司的Ｄｙｎａｆｏｒｍ，法国ＥＳＩ集团的ＰＡＭ系列软件，德国ＡｕｔｏＦｏｒｍ工程股份有限公司的ＡｕｔｏＦｏｒｍ，国内有吉林金网格模具工程研究中心的ＫＭＡＳ软件，北航的ＳｈｅｅｔＦｏｒｍ，华中科技大学的Ｖｆｏｒｍ等。本文着重探讨ＡｕｔｏＦｏｒｍ及其应用。 １． 概述：ＡｕｔｏＦｏｒｍ与板料成形技术 ＡｕｔｏＦｏｒｍ工程有限公司包括瑞士研发与全球市场中心和德国工业应用与技术支持中心，其研发和应用的阶段主要有：１９９１年实现自适应精化（ａｄａｐｔｉｖｅ ｒｅｆｉｎｅｍｅｎｔ）网格；１９９２年采用隐式算法（ｉｍｐｌｉｃｉｔ ｃｏｄｅ）并与１９９３年开发出板成形模拟分析的专用软件；１９９４年实现对ＣＡＤ数据的自动网格划分；１９９５年开始工业应用； １９９６年实现对ＣＡＤ数据的自动倒园（ａｕｔｏｍａｔｉｃ ｆｉｌｌｅｔｉｎｇ）；１９９７年采用Ｏｎｅ－ｓｔｅｐ（一步成形）代码实现工艺补充面（ａｄｄｅｎｄｕｍ）的自动设计；１９９８年实现压料面（ｂｉｎｄｅｒ）的自动生成；２０００年实现快速交互式模具设计。它是专门针对汽车工业和金属成形工业中的板料成形而开发和优化的，用于优化工艺方案和进行复杂型面的模具设计，约９０％的全球汽车制造商和１００多家全球汽车模具制造商和冲压件供应商都使用它来进行产品开发、工艺规划和模具研发，其目标是解决“零件可制造性（ｐａｒｔ ｆｅａｓｉｂｉｌｉｔｙ）、模具设计（ｄｉｅ ｄｅｓｉｇｎ）、可视化调试（ｖｉｒｔｕａｌ ｔｒｙｏｕｔ）”。它将来自世界范围内的许多汽车制造商和供应商的广泛的诀窍和经验融入其中，并采取用户需求驱动的开发策略，以保证提供最新的技术。 ＡｕｔｏＦｏｒｍ的特点：１）它提供从产品的概念设计直至最后的模具设计的一个完整的解决方案，其主要模块有Ｕｓｅｒ－Ｉｎｔｅｒｆａｃｅ（用户界面）、Ａｕｔｏｍｅｓｈｅｒ（自动网格划分）、Ｏｎｅｓｔｅｐ（一步成形）、ＤｉｅＤｅｓｉｇｎｅｒ（模面设计）、Ｉｎｃｒｅｍｅｎｔａｌ（增量求解）、Ｔｒｉｍ（切边）、Ｈｙｄｒｏ（液压成形），支持Ｗｉｎｄｏｗｓ和Ｕｎｉｘ操作系统。２）特别适合于复杂的深拉延和拉伸成形模的设计，冲压工艺和模面设计的验证，成形参数的优化，材料与润滑剂消耗的最小化，新板料（如拼焊板、复合板）的评估和优化。３）快速易用、有效、鲁棒（ｒｏｂｕｓｔ）和可靠：最新的隐式增量有限元迭代求解技术不需人工加速模拟过程，与显式算法相比能在更短的时间里得出结果；其增量算法比反向算法有更加精确的结果，且使在ＦＬＣ－失效分析里非常重要的非线性应变路径变得可行。即使是大型复杂制件，经工业实践证实是可行和可靠的。４）ＡｕｔｏＦｏｒｍ带来的竞争优势：因能更快完成求解、友好的用户界面和易于上手、对复杂的工程应用也有可靠的结果等，ＡｕｔｏＦｏｒｍ能直接由设计师来完成模拟，不需要大的硬件投资及资深
excel表单控件与ActiveX控件概念
工作表中的表单、表单控件和ActiveX 控件概念 是的，确实如此。在Microsoft Excel 中，使用少量或者无需 使用Microsoft Visual Basic for Applications (VBA) 代码即可 创建出色的表单。使用表单以及可以向其中添加的许多控件和 对象，您可以显著地增强工作表中的数据项并改善工作表的显 示方式。 ? ? 什么是表单？ 无论是打印表单还是联机表单都是一种具有标准结构和格式的文档，这种文档可让用户更轻松地捕获、组织和编辑信息。 ?打印表单含有说明、格式、标签以及用于写入或键入数据的空格。您可以使用Excel 和Excel 模板创建打印表单。 ?联机表单包含与打印表单相同的功能。此外，联机表单还包含控件。控件是用于显示数据或者更便于用户输入或编辑数据、执行操作或进行选择的对象。通常，控件可使表单更便于使用。例如，列表框、选项按钮和命令按钮都是常用控件。通过运行(VBA) 代码，控件还可以运行指定的和响应事件，如鼠标点击。 您可以使用Excel 通过多种方式创建打印表单和联机表单。 Excel 表单的类型 您可以在Excel 中创建多种类型的表单：数据表单、含有表单和ActiveX 控件的工作表以及VBA 用户表单。可以单独使用每种类型的表单，也可以通过不同方式将它们结合在一起来创建适合您的解决方案。 数据表单
为在无需水平滚动的情况下在单元格区域或表格中输入或显示一整行信息提供了一种便捷方式。您可能会发现，当数据的列数超过可以在屏幕上查看的数据列数时，使用数据表单可以使数据输入变得更容易，而无需在列之间进行移动。如果以标签的形式将列标题列出的文本框这一简单表单足以满足您的需求，而且您不需要使用复杂的或自定义的表单功能（例如列表框或调节钮），则可以使用数据表单。 Excel 可以为您的或自动生成内 置数据表单。数据表单会在一个对 话框中将所有列标题都显示为标 签。每个标签旁边都有一个空白文 本框，您可以在其中输入每一列的 数据，最多可以输入32 列数据。 在数据表单中，您可以输入新行， 通过导航查找行，或者（基于单元 格内容）更新行及删除行。如果某 个单元格包含，则公式结果会显示 在数据表单中，但您不能使用数据 表单更改该公式。 含有表单和ActiveX 控件的工作表 工作表是一种类型的表单，可让您在网格中输入数据和查看数据，Excel 工作表中已经内置了多种类似控件的功能，如注释和数据验证。单元格类似于文本框，因为您可以在单元格中输入内容以及通过多种方式设置单元格的格式。单元格通常用作标签，通过调整单元格高度和宽度以及合并单元格，您可以将工作表用作简单的数据输入表单。其他类似控件的功能（如单元格注释、超链接、背景图像、数据验证、条件格式、嵌入图表和自动筛选）可使工作表充当高级表单。 为增加灵活性，您可以向工作表的“”添加控件和其他绘图对象，并将它们与工作表单元格相结合和配合。例如，您可以使用列表框控件方便用户从项目列表中选择项目。还可以使用调节钮控件方便用户输入数字。 因为控件和对象存储在绘图画布中，所以您可以显示或查看不受行和列边界限制的关联文本旁边的控件和对象，而无需更改工作表中数据网格或表的布局。在大多数情况下，还可以将其中许多控件链接到工作表中的单元格，而无需使用VBA 代码即可使它们正常工作。您可以设置相关属性来确定控件是自由浮动还是与单元格一起移动和改变大小。例如，在对区域进行排序时，您可能有一个希望与基础单元格一起移动的复选框。不过，如果您有一个希望一直保持在特定位置的列表框，则您可能希望它不与其基础单元格一起移动。 Excel 有两种类型的控件：表单控件和ActiveX 控件。除这两个控件集之外，您还可以通过绘图工具（如、、SmartArt 图形或文本框）添加对象。 以下部分介绍这些控件和绘图对象，此外，还更为详细地介绍如何使用这些控件和对象。
.NET4.0 用户控件的概述
https://www.wendangku.net/doc/872119626.html,4.0 用户控件的概述 用户控件是页面的一段，包含了静态HTML代码和服务器控件。其优点在于一旦创建了一个用户控件，可以在同一个应用的多个页面中重用。并且，用户可以在Web用户控件中，添加该控件的属性、事件和方法。 1．什么是用户控件 用户控件（后缀名为.ascx）文件与https://www.wendangku.net/doc/872119626.html,网页窗体(后缀名为.aspx)文件相似。就像网页窗体一样，用户控件由用户接口部分和控制标记组成，而且可以使用嵌入脚本或者.cs代码后置文件。用户控件能够包含网页所能包含的任何东西，包括静态HTML内容和https://www.wendangku.net/doc/872119626.html,控件，它们也作为页面对象（Page Object）接收同样的事件(如Load和PreRender)，也能够通过属性（如Application,Session,Request 和Response）来展示https://www.wendangku.net/doc/872119626.html,内建对象。 用户控件使程序员能够很容易地跨Web应用程序划分和重复使用公共UI功能。与窗体页相同，用户可以使用任何文本编辑器创作用户控件，或者使用代码隐藏类开发用户控件。 此外，用户控件可以在第一次请求时被编译并存储在服务器内存中，从而缩短以后请求的响应时间。与服务器端包含文件（SSI）相比，用户控件通过访问由https://www.wendangku.net/doc/872119626.html,提供的对象模型支持，使程序员具有更大的灵活性。程序员可以对在控件中声明的任何属性进行编程，而不只是包含其他文件提供的功能，这与其他任何https://www.wendangku.net/doc/872119626.html,服务器控件一样。 此外，可以独立于包含用户控件的窗体页中除该控件以外的部分来缓存该控件的输出。这一技术称作片段缓存，适当地使用该技术能够提高站点的性能。例如，如果用户控件包含提出数据库请求的https://www.wendangku.net/doc/872119626.html,服务器控件，但该页的其余部分只包含文本和在服务器上运行的简单代码，则程序员可以对用户控件执行片段缓存，以改进应用程序的性能。 用户控件与普通网页页面的区别是： ●用户控件开始于控件指令而不是页面指令。 ●用户控件的文件后缀是.ascx，而不是.aspx。它的后置代码文件继承于 https://www.wendangku.net/doc/872119626.html,erControl类.事实上，UserControl类和Page类都继承于同一个 TemplateControl类，所有它们能够共享很多相同的方法和事件。 ●没有@Page指令，而是包含@Control指令，该指令对配置及其他属性进行定义。 ●用户控件不能被客户端直接访问，不能作为独立文件运行，而必须像处理任何控件一 样，将它们添加到https://www.wendangku.net/doc/872119626.html,页中。 ●用户控件没有html、body、form元素，但同样可以在用户控件上使用HTML元素和 Web控件。 用户可以将常用的内容或者控件以及控件的运行程序逻辑，设计为用户控件，
第六章 对话框控件
学习目标： ?掌握CommonDialog。 ?掌握文件操作相关的对话框。 ?理解打印对话框。 6.1对话框： 对话框是一种用户界面接口，用于同用户进行交互，完成一些特定的任务，简单的对话框有对用户操作进行提示的对话框，对重要操作要求用户进行决定的交互对话框等。 这类任务能被独立出来，作为通用的交互处理过程。这些能被独立出来作为通用交互过程的任务常见如下一些： （1）文件选取。 （2）保存设置。 （3）路径选取。 （4）字体选取。 （5）颜色选取。 （6）打印设置。 （7）打印预览框。 在.NET中这些组件是在https://www.wendangku.net/doc/872119626.html,monDialog的基础上发展而来。
6.1.1Common pialog： CommonDialog是.NET中对话框组件的基础，它是System.Windows.Forms命名空间下的一个抽象类，在程序中不能直接使用。 CommonDialog公开了2个方法和一个属性，即：ShowDialog()/ShowDialog(IWin32Window)方法和Reset（）方法以及Tag属性。 ShowDialog是用于显示对话框。ShowDialog()有一个重载形式：ShowDialog（IWin32Window），IWin32Window在这里指一个窗口句柄，在调用中，这个参数应该被赋值成要显示的对话框的父窗体。 注意：句柄是Window中的一个常用词语，可以把它理解为一个标识符号，只是这个标识符号是一个数字。相应的窗口句柄就是窗口的标标识符。 Reset方法： 使用过程中可能改变初始值，当需要让所有的初值回到原来的状态时，调用Reset能达到目的。 Tag属性： Tag没有具体含义，它可以让用户在对话框控件中存储、维护自己的数据。这个数据由用户自己的代码解释。 对话框的返回值（ShowDialog的返回值）： 对话框通过调用ShowDialog()调用后，返回一个类型为DialogResult 值，其中DialogResult.OK指出用户成功完成了操作，成功选取了文
vf表单控件的使用说明
一、标签 标签能够显示多个字符构成的文本，用于设计表单上所需的文字性提示信息。标签和大多数控件的不同点在于运行表单时不能用《tab》键来选择标签。 常用的标签属性及其作用如下。 1、Caption：确定标签处显示的文本。 2、Visible：设置标签可见还是隐藏。 3、AutoSize：确定是否根据标签上显示文本的长度，自动调整标签大小。 4、BackStyle：确定标签是否透明。 5、WordWrap：确定标签上显示的文本能否换行。 6、FontSize：确定标签上显示文本所采用的字号。 7、FontName：确定标签上显示文本所采用的字体。 8、ForeColor：确定标签上显示的文本颜色。 二、命令按钮和命令按钮组 在各种窗口或对话框中几乎都要使用一个或多个命令按钮。一旦用户单击一个命令按钮，就可实现某种规定的操作。例如，各种对话框中的“确定”按钮，当用户单击时将结束对话框的操作。 VisualForPro中的命令按钮控件同样用于完成特定的操作。操作的代码通常放在命令按钮的“单击”事件（即Click Event）代码中。这样，运行表单时，当用户单击命令按钮时便会执行Click事件代码。如果在表单运行中，某个命令按钮获得了焦点（这时，这个命令按钮上会比其他命令按钮多一个线框），则当用户按下《Enter》键或空格键时，也会执行这个命令按钮的Click时间代码。 常用的命令按钮属性及其作用如下： 1、Caption：设置在按钮上显示的文本。 2、Default：在表单运行中，当命令按钮以外的某些控件（如文本框）获得焦点时，若 用户按下《Enter》键，将执行Default属性值为.T.的那个命令按钮的click事件代码。 3、Cancel：如果设置该属性值为.T.，则当用户按下
MFC对话框程序中的各组件常用方法
MFC对话框程序中的各组件常用方法： Static Text: 将ID号改成唯一的一个，如：IDC_XX，然后进一次类向导点确定产生这个ID，之后更改Caption属性： GetDlgItem(IDC_XX)->SetWindowText(L"dsgdhfgdffd"); 设置字体： CFont *pFont = new CFont; pFont->CreatePointFont(120,_T("华文行楷")); GetDlgItem(IDC_XX)->SetFont(pFont); Edit Control: 设置文本： SetDlgItemText(IDC_XX,L"iuewurebfdjf"); 获取所有输入： 建立类向导创建一个成员变量（假设是shuru1，shuru2……）类型选value，变量类型任选。 UpdateData(true); GetDlgItem(IDC_XX)->SetWindowText(shuru1); 第一句更新所有建立了变量的对话框组件，获取输入的值。第二句将前面的IDC_XX的静态文本内容改为shuru1输入的内容。 若类型选用control: 1.设置只读属性： shuru1.SetReadOnly(true); 2.判断edit中光标状态并得到选中内容(richedit同样适用) int nStart, nEnd; CString strTemp; shuru1.GetSel(nStart, nEnd); if(nStart == nEnd) { strTemp.Format(_T(" 光标在%d" ), nStart); AfxMessageBox(strTemp); } else { //得到edit选中的内容 shuru1.GetWindowText(strTemp); strTemp = strTemp.Mid(nStart,nEnd-nStart); AfxMessageBox(strTemp); } 其中nStart和nEnd分别表示光标的起始和终止位置，从0开始。strTemp.Format 方法用于格式化字符串。AfxMessageBox(strTemp)显示一个提示对话框，其内容是字符串strTemp。 strTemp = strTemp.Mid(nStart,nEnd-nStart)返回一个被截取的字符串，从nStart开始，长度为nEnd-nStart。如果nStart == nEnd说明没有选择文本。 注：SetSel(0,-1)表示全选;SetSel(-1,i)表示删除所选。
教学设计表单控件--选项按钮组
优秀课堂教学设计 课题：教表单控件选项按钮组 师：教材分马冬艳析：本节课是选自中等职业学校计算机技术专业的《数据库应用技术 VISUAL FOXPRO6.0 》中第六章表单设计中的第三节的内容。节课是在同学们 已经掌握了几种基本表单控件的基础上，进一步学习选项按扭组控件。重点：选项 按钮组的基本属性和特有属性难点：选项按钮组的应用能力目 1）标：通过了解选项按钮组的特性，并予以适当的启发，让学生能够利用此 2）控件具有创造性的设计出实用表单，培养学生的创造力。 3）知识目标：熟知选项按钮组的特性并熟练应用。情感目标：通过讨论增进同学们的感情交流和知识交流。由于书上对本节的内容实例较少且实例多是在以往例 题的基础上添加上此控因此控件属性突出不明显，为此我特地 专对此控件的属性设计了一道例题，不但能突出这个控件的特有属性，而（4） 且能极大的提高学生的学习兴趣，有利有的突出了重点问题，为解决难点课程重组：（5） 做好了铺垫。在精心设置例题的基础上增加了让学生自己根据控件属性设置问题的环节，不但能增加学生学习的兴趣而且有利于学习对本节课的内容进行深层次的思考，从而达到突破难点的目的。学生在学习本节课之前已经学习了一些控件，对于控件的学习已经有了一定学习经验，知道在学习控件的学习过程中应该注意哪些地方。但是由于控件学习的比较多，而且有很多相似的地方学生容易产生厌烦情绪，为了解决这个问题，要在引入此控件时设置好问题情境，引发学生学习兴趣，且鼓励学生进行大胆的学情分析：设想，培养同学们的创造思维能力。根据学生学习能力水平的不同在请同学们上前操作时，按照要操作的内容有选择性的挑选学生上来操作，在做简单操作时挑选那些平时操作不是很熟练且胆子比较小的同学，在培养他们胆量的同时通过完成一些简单操作激发他们的信心。对于那些较有难度且需要进行一不思考的问题，找一些底子比较好但是又不会很快把这个问题解决出来的同学来做，在他做的过程
ASP NET基础知识
https://www.wendangku.net/doc/872119626.html,的两种编码方式是什么，什么是代码内嵌，什么是代码后置？Web页面的父类是谁？ 代码内嵌和代码后置。代码内嵌把业务逻辑编码和显示逻辑编码交叉使用。代码后置式业务逻辑代码和显示逻辑代码分开使用。system.web.ui.page 2.Web控件的AutoPostBack属性的作用是什么？ 控件的值改变后是否和服务器进行交互（自动回传） 3.验证服务器控件有哪些，他们有哪些常用的属性，ControlToValidate属性的作用是什么？有哪两种服务器控件？ RequiredFieldValidator：controltovalidate（验证的控件ID，共有的属性），text,ErrorMessage||||（dropdownlist控件验证时InitialValue属性是如果用户没有改变初始值，会验证失败）CompareValidator:controltocompare（要进行对比的控件），type（比较类型设置），operator(比较运算符，默认为等于)，ValueToCompare（进行比较的值） RangeValidator:type（验证类型（5种）），MaximumValue（最大值），MinimumValue（最小值）（包括上下限） RegularExpressionValidator:ValidationExpression（设置要匹配的正则表达式）ValidationSummary:showMessageBox(是否显示弹出的提示消息)，ShowSummary（是否显示报告内容） HTML服务器控件和web服务器控件 4.什么是Session，如何进行Session的读写操作，使用什么方法可以及时释放Session？Session 是用于保持状态的对象。Session 允许通过将对象存储在Web服务器的内存中在整个用户会话过程中保持任何对象。 通过键值对的方式进行读写；clear()和abandon()方法 5.运行https://www.wendangku.net/doc/872119626.html,程序需要安装和配置什么，.NET Framework是不是必须要安装？ 安装IIS和.NET Framework 必须安装 https://www.wendangku.net/doc/872119626.html,配置信息分别可以存储在什么文件中？ web.config文件和machine.config文件中 7.常用服务器控件，如Label、Button、TextBox、HyperLink、DropdownList的常用属性有哪些？label:text ,forecolor,visible Button:CommandName,CauseValidation, TextBox:AutopostBack,TextMode Hyperlink:NavigateUrl(单击Hyperlink时跳转的Url)，Text，Target（设置NavigateUrl属性的目标框架），ImageUrl（设置Hyperlink中显示图片文件的Url） Dropdownlist:AutoPostBack 8.XMLHttpRequest对象的常用属性和方法有哪些？ 方法是open（）和send() 属性：ReadyState和Status,ResponseText,ResponseXML,ResponseStream https://www.wendangku.net/doc/872119626.html,中的常用的指令有哪些？谈谈这些指令的常用属性的作用？
表单控件常用属性、事件及方法英中对照
VFP表单/控件常用属性、事件及方法英中对照 ——属性—— Name：表单或控件名 Caption：标题文字 AutoCenter：自动居中 AutoSize：自动大小 ForeColor：前景色 BackColor：背景色 Closable：可关闭 Movable：可移动 Width：宽度 Height：高度 Icon：图标 Visible：可见 Font*：字体、字号等 Enabled：能用 ButtonCount：命令按钮组、选项组控件中控件的个数 Buttons（1）：命令按钮组、选项组控件中第一个控件；Buttons（2）命令按钮组、选项组控件中第二个控件；…… value：表示组控件中选中的是第几个控件 或文本框中的内容 或列表框中选择的内容 等 PasswordChar：文本框用于输密码时显示的符号 ControlSource：和控件绑定的内存变量或字段SelStart：编辑框中选定内容的开始位置SelLength：编辑框中选定内容的长度SelText：编辑框中选定的内容 ListCount：列表框中可供选择的内容数 List（1）表示列表框中的第一项内容，List（2）表示列表框中的第二项内容，……RowSourceType：列表框中内容的给出方式RowSource：列表框中内容来自的字段名等MultiSelect：1或.t.时允许多项选择 Selected（1）为真，第一项被选；Selected（2）为真，第二项被选；……。 Text：下拉列表框中输入的内容Recordsource：表格控件绑定的表PageCount：页框中页面的个数 Pages（1）表示页框中的第一个页面，Pages （2）表示页框中的第二个页面，……ActivePage：页框中的活动页面号Increment：微调每次的变化量SpinnerHighValue：鼠标调整时的最大值SpinnerLowValue：鼠标调整时的最小值KeyboardHighValue：键盘输入时的最大值KeyboardLowValue：键盘输入时的最小值Value：微调的当前值 Picture：图像控件对应的图像 Stretch：图像的显示方式 Interval：计时器定时的时间间隔，单位毫秒 ——事件—— Load：装入事件 Init：初始化事件 Destroy：表单关闭前发生的事件Unload：表单关闭时发生的事件Click：单击事件 DblClick：双击事件 RightClick：右键事件 GotFocus：得到焦点事件 LostFocus：失去焦点事件 Timer：计时器指定的时间间隔到时发生 Error：执行对象事件代码出错时发生——方法—— Release：关闭表单Refresh：表单刷新Show：显示表单Hide：隐藏表单SetFocus：将焦点放到控件中 AddItem（内容项）：向列表框中增加数据项RemoveItem（位置）：从列表框中删数据项
实验四VBNET程序设计基础和常用控件
实验四 https://www.wendangku.net/doc/872119626.html,程序设计基础和常用控件 一、实验目的 本实验主要了解面向对象程序设计语言https://www.wendangku.net/doc/872119626.html,基本语言元素包括集成开发环境、语言基础、基本控制结构、过程、常用控件和界面设计。通过本实验，读者将学会一些主要的面向对象的设计方法并可以利用https://www.wendangku.net/doc/872119626.html,完成简单的应用程序开发。 二、实验环境 Microsofe Visual Studio .NET 2008 三、实验内容 1．设计一个Visual 的应用程序，窗体上有一个多行文本框和3个命令按钮，程序界面如图1所示。要求应用程序运行时，当单击窗体上【显示文本信息】按钮，文本框中显示红色文字“我喜欢https://www.wendangku.net/doc/872119626.html,，因为它简单易学，使用方便。”当单击窗体上【改变背景色】按钮，文本框的背景色变为黄色。当单击窗体上【结束】按钮，程序结束。保存该应用程序。【实验步骤】： 1）创建工程：打开Visual Studio 后，点击左上角的新建项目，选中“模板”，展开选择Visual Basic，再选中Windows桌面，再在左边的类型中选择“Windows窗体应用程序”，在下方为此项目命名为“Win dowsApplication4.1”
2）先打开“工具箱”：展开左上角的“视图”，点击工具箱。 3)修改Form1的名称：右键选中From1,点击“属性”，在新弹出的属性菜单栏中，找到“Text”这个属性，将右边的“From1”改为“第一个https://www.wendangku.net/doc/872119626.html,实验”即可。 4）设置一个普通文本框：在工具栏中，选中公共空间中的TextBox，然后拖入右边的设计窗口中，然后鼠标移到TextBox后，鼠标左键按住不放可以移动此控件。 5）调整文本框的大小：鼠标移动到文本框的左右边缘，鼠标箭头会变成一个左右的箭头，
autoform详细设置
Autoform中整形的设置过程 以S21项目中的一个产品为例，介绍在Autoform中设置整形的过程。 1.产品名称：左/右门槛后部本体，产品图号：S21-5101931/2 料厚：1.2 材质：ST12 如图所示： 2.此产品由（1）拉延、（2）修边冲孔、（3）翻边整形、（4）冲孔侧冲孔切断四序完成（左右 件共模）。仅介绍第三序翻边整形的设置过程。 3.设置过程 3.1 过程准备 3.1.1按“Autoform操作规范”进行工艺补充（如图所示），并进行拉延序的计算，拉延序的计算 结果达到最佳时，方可进行后序的计算。 3.1.2将修边线（必要时将修边后的产品型以.igs 格式输出以便在Autoform中计算整形和翻 边时提取修边线）、产品数型以.igs 格式输出。
3.2 在Autoform 中对整形过程进行设置： 3.2.1 打开拉延序的.sim 文件，在此基础上进行整形过程的设置。 3.2.2 打开几何构型（Geometry Generator ）对话框，导入产品数型，导入过程如图所示： （1） （2） （3） 具体步骤为： ① 打开Geometry Generator 对话框，如图（1）所示； ② 在File 的下拉菜单中选择Import[如图（2）所示]；弹出如图（3）所示的对话框； ③ 选择New Geometry ，在地址栏中输入文件所在地址，单击 OK 。
3.2.3 打开仿真参数输入（Input Generator ）对话框，进行仿真参数设置。 3.2.3.1 模具结构的运动过程 ① 在进行仿真参数设置以前，首先要了解模具结构的运动过程。 翻边：向上翻边是通过上压料芯和下托料芯夹紧料与下模镶块的相对运动来完成的； 向下翻边是通过上压料芯和下模压紧料与上模镶块的相对运动来完成的。 整形：整形是通过上（或下）模镶块与上压料芯（或下托料芯）的相对运动来完成。 ② 此产品需要向上翻边，且拉延修边后的产品型和翻边前的产品型不一致，因此在 Autoform 中进行仿真参数设置时要相应的增加上压料芯、上模镶块、下托料芯和下模镶块这些工具；同样，在运动过程设置中也需要增加修边、定位（制件）、闭合、成型这些运动过程(其中成型过程需要两个，分别为：翻边、整形的成型过程)，先将修边后的产品型整形，再翻边得到最终的产品型。 （4）Input Generator 中的Tools 对话框
OA常用控件的用法
OA工作流的表单设计器中最常用控件的用法 如果想要设计制作精确、合理的OA工作流程，最基本的条件是设计出最合适的工作表单，而表单的制作最关键的是熟练掌握各个控件的使用方法。 下面就以最常用的几个控件跟大家分享一下它们在工作表单的制作过程中的用法。
控件类型及其用 第一，单行输入框。 单行输入框是最简单的空间，就是为表单添加一个可以输入内容的空，一般是用来填写比较简短的内容，比如：名字、手机号等。 ?如上图所示设置了单行输入框的属性后，就会在表单中出现下图所示的样式。 ?第二，多行输入框。 性质跟单行输入框类似，这个控件的内容也是完全由填写表单的用户手填。但多行输入框一般是用在输入内容较长的地方，比如一个较长的地址。
?如下图所示就是一个设置好的多行输入框在表单中显示的样式。 ?第三，下拉菜单。 这个很好理解，下拉菜单包含所有可能的选项。然后填写表单的用户可以通过下拉菜单选择需要的选项。
?第四，单选框。 单选框的含义我们都知道，就是设置多于一个的选项，而用户填写表单的时候只能从中选择一个选项。 ?比如下图所示的一个同意或不同意，只能选择其中一个选项。
?第五，多选框。 多选框的功能其实是只在表单中画一个可以打勾的小框，多选框有多少选项，就设置多少个多选框，然后在每个多选框后面自定义选项内容。 ?如下图所示就是一个多选框的样式，其中，火车、汽车、飞机和轮船这四个选项是在表单中定义的。 ?第六，列表控件。 这个列表控件其实是不经常用到的。起作用是相同格式记录的动态输入，可以根据实际需要灵活新增行数录入相应数据。 使用这个控件，是可以设置好列表头。列表控件支持多种输入类型，包括单行输入框、多行输入框、下来菜单、单选框、复选框和日期，满足多方面的需求； 而且支持自动计算和合计，使用通用运算符+、-、*、/、%等，可以实现列表项目的自动计算输入。其中列表计算项目是不可人工输入的。 如果用户在设计表单的时候确实用到了这个控件，可以设置上一两行试一下，看完表单效果后就知道该如何设置。
aspnet常用控件介绍
Label控件 功能说明：用于显示文本，提示信息，如窗体标题，文本框的标题 命名前缀：Lbl ASPX代码：
最新AUTOFORM分析拉延成型资料
常见缺陷及解决办法 1．拉延开裂 开裂是拉延工序中最为常见的缺陷之一，其表现为出现破裂或裂纹，产品部分如果出现破裂或者裂纹将被视为不合格产品，所以必须予以解决。产生开裂的原因大致有： （1）产品工艺性不好，如R角过小、型面变化剧烈、产品深度较深以及材质成形性能差等。 （2）工艺补充、压边圈的设计不合理。 （3）拉延筋设计不合理，不能很好的控制材料流动。 （4）压边力过大。 （5）模具型面表面粗糙度达不到要求，摩擦阻力大。 （6）模具加工精度差，凸凹模间隙小，板料流动性差。 目前，主要通过改善产品工艺性、设计合理的坯料形状、增加刺破刀、加大R角、合理设计工艺补充及压料面、调整拉延筋阻力及压边力和模面镜面处理等方式来解决拉延开裂问题。 2．起皱 起皱是拉延工序中另一个常见的缺陷，也是很难解决的板件缺陷。板件发生起皱时，会影响到模具的寿命以及板件的焊接，板件发生叠料时还会使模具不能压合到底，从而成形不出设计的产品形状，同时，由于叠料部位不能进行防锈处理，容易导致板件生锈而影响到板件的使用寿命，给整车安全造成隐患。 目前主要从产品设计及工艺设计上来解决起皱问题，归纳起来有以下几点： （1）产品设计时尽量避免型面高低落差大、型面截面大小变化剧烈，在不影响板件装配的情况下，在有可能起皱的部位加吸皱包。 （2）工艺上可以考虑增加整形工序。 （3）分模线调整。随着分模线的调整，往往会伴随着开裂缺陷的产生，目前主要通过使用CAE软件来分析确定合理的分模线位置。 （4）在工艺补充面上增加吸料筋、工艺台阶等，将多余的料消化掉。 （5）合理设计拉延筋，以确保各个方向进料均匀为目标。 （6）当开裂与起皱同时存在，且起皱不被允许时，一般先解决起皱再解决开裂。 AutoForm模拟分析算法
4 对话框及常用控件 (第四章 对话框和常用控件)
1．什么是对话框？它分为哪两类？这两类对话框有哪些不同？ 答：对话框是一种特殊的窗口，主要功能是输出信息和接收用户的输入。对话框分为有模式对话框和无模式对话框。当一个有模式对话框打开时，用户只能与该对话框进行交互，而其他用户界面对象收不到输入信息。而无模式对话框打开时，用户可以同时打开其他窗口对象，操作完毕后，又可用鼠标或其他方式激活该窗口。 2．什么是对话框模板、对话框资源和对话框类？ 答：对话框模板是一个描述对话框的内存结构，用于添加控件及其布局。对话框资源指快捷键、对话框、菜单、字符串、工具栏按钮、图表、版本信息等。对话框类用于实现对话框功能。 3．对一个对话框编程一般经过几个步骤？ 答：1. 在资源编辑器中画对话框，添加控件，设定控件位置、大小、ID和其它属性； 2. 定义对话框回调函数，添加控件的事件处理函数； 3. 注册对话框函数 4、什么是控件？根据控件的性质可以将控件分为几类？ 答：在Windows中所用的按钮控件是用来实现一种开与关的输入。 常见按钮类型：按键按钮、单选按钮、复选框按钮。 5．向对话框添加一个常用控件的方法有哪些？这些方法是否使用于ActiveX控件？ 答：1、先点击控件，然后在对话框上单击， 2、先点击控件，然后在对话框上点住不放，画出像要的大小。 否。 6．什么是DDV/DDX技术？如何使用这种技术？ 答：DDX（对话框数据交换）机制用来初始化对话框中的数据，并向应用程序返回数据，它使得用户向对话框加载对象数据和当对话框关闭时恢复其中的数据这两个过程自动化。 DDV（对话框数据验证有效性）机制用于将数据返回成员变量之前将数据的长度和范围有效化。 7.什么是空间的通知消息？它在编程中起哪些作用？ 答：控件消息由按钮（BN_）、编辑框（EN_）、组合框（CBN_）和列表框（LBN＿）等产生。控件通过向父窗口发送控件通知消息来表明发生了某种事件。
AutoForm介绍
AutoForm介绍 当代汽车和现代模具设计制造技术都表明，汽车覆盖件模具的设计制造离不开有效的板成形模拟软件。世界上大的汽车集团，其车身开发与模具制造都要借助于一种或几种板成形模拟软件来提高其成功率和确保模具制造周期。我经过一段时间对AutoForm软件的自学，对AutoForm进行简单的介绍。 AutoForm工程有限公司简介 AutoForm工程有限公司成立于 1995 年，总部位于瑞士苏黎士，主要从事其软件的源代码开发及全球市场战略策划。AutoForm工程有限公司包括瑞士研发与全球市场中心和德国工业应用与技术支持中心，它是专门针对汽车工业和金属成形工业中的板料成形而开发和优化的，用于优化工艺方案和进行复杂型面的模具设计，约90%的全球汽车制造商和100多家全球汽车模具制造商和冲压件供应商都使用它来进行产品开发、工艺规划和模具研发，其目标是解决“零件可制造性(part feasibility)、模具设计(die design)、可视化调试(virtual tryout)”。它将来自世界范围内的许多汽车制造商和供应商的广泛的诀窍和经验融入其中，并采取用户需求驱动的开发策略，以保证提供最新的技术。 AutoForm软件的主要模块： 1．“一步法 OneStep”快速分析模块“O” (快速仿真), 2．“工件设计TM PartDesigner TM”模块“b”, 3．“料片与落料模设计TM BlankDesigner TM”模块, 4．“工艺规划与预算核算模模块TM CostCalculator TM” / “n” 5．“落料排料 NEST”模块“N”/ “n”, 6．“模具设计TM DieDesigner TM”模块“D”/ “d”, 7．“增量法 Incremental”精密分析模块“A”(过程精密仿真), 8．“模具材料及表面处理分析模块TM DieAdviser TM” / “i” 9．“修边线设计Trim”模块“t”, 10．“回弹补偿SpringbackCompensator TM模块” 11．“技术专家全自动工艺优化Sigma”模块“p”, 12．“管胀成形精密分析Hydro”模块“H”, 13．“管胀成形模具设计TM HydroDesigner TM”模块“Y/y”, 14．“模拟项目管理TM ProjectManager TM”模块“j”, 15．“模拟报告动态关联生成器TM ReportManager TM”模块“r”, 13.“CATIA V4/V5接口集成”模块“c5”, 14. “UG接口集成”模块“u”. AutoForm软件的特点 用一句话可以概括AutoForm软件的特点和优势，即：“金属板材成形从产品概念到批量生产完整工艺流程的集成化智能化解决方案”。具体来说： （1）它提供从产品的概念设计直至最后的模具设计的一个完整的解决方案，其主要模块有User-Interface(用户界面)、Automesher(自动网格划分)、Onestep(一步成形)、DieDesigner(模面设计)、Incremental(增量求解)、Trim(切边)、Hydro(液压成形)，支持Windows和Unix操作系统。 （2）特别适合于复杂的深拉延和拉伸成形模的设计，冲压工艺和模面设计的验证，成形参数的优化，材料与润滑剂消耗的最小化，新板料(如拼焊板、复合板)的评估和优化。 （3）快速易用、有效、鲁棒(robust)和可靠：最新的隐式增量有限元迭代求解技术不需人工加速模拟过程，与显式算法相比能在更短的时间里得出结果；其增量算法比反向算法有更加精确的结果，且使在FLC-失效分析里非常重要的非线性应变路径变得可行。即使是大型复杂制件，经工业实践证实是可行和可靠的。
从零开始学VC系列教程 二.对话框及常用控件实验
从零开始学VC系列教程二. 对话框及常用控件实验 恭喜你,进入VC学习的第二节了.这一节是人机交互的基础.所谓人机交互,说通俗点就是与机器对话.然而我们现在的技术还不能像科幻片里一样与机器人直接说话就行了.所以,我们的操作意图还得通过文本输入,命令按钮等等来实现. 本节内容:学会对话框调用及一些常用控件的使用方法. 学习目的:学习人机交互,为软件开发提供界面基础. 1.新建工程.参考第一节的方法新建一个工程,名字为Eg02完成后如下图 细心的朋友一定会发现.新建的工程里还有一个对话框,ID名是IDD_ABOUTBOX这个是做什么用的呢?我们用到的软件都会有一个版权声明.通过第一章的学习,大家应该知道怎么观看这个IDD_ABOUTBOX对话框了吧.没错!双击IDD_ABOUTBOX就可以了.我们会看到如下的一个对话框 这就是我们这个程序的关于对话框,一般用于版权声明及版本号标识.大家看到的这个对话框里有两个静态文本框和一个图像框(Picture),静态文本框我们在前一节已经介绍过了.大家可以修改一下版权所有这一行,填什么都可以,签个大名也行.完成以后你一定想看看效果,这个对话框怎么打开呢?其实VC已经为我们做好了.先按F7编译,然后按F5运行.大家可以看到
程序运行了. 单击应用程序图标,就会出现一个菜单,选最后一个[关于Eg02],关于对话框就弹出来了. 当然,这是系统为我们做好的.自己怎么在程序中调用这个对话框呢?为了演示,首先参考第一节的内容添加一个按钮,然后把按钮的ID改为IDC_BTN_ABOUTME,把标题,也就是Caption 改为[关于].最终效果如下 下面我们为按钮添加代码.相信大家一定还记得怎么进入代码吧..对了,双击[关于]按钮,在弹出的对话框中点[确定]就可以了.为了让大家更好的理解下面的操作,我们先要解释一下关于对话框的类.VC向导会为关于对话框建立一个类,大家看看下面的图