a r X i v :c o n d -m a t /9712114v 1 [c o n d -m a t .s t a t -m e c h ] 10 D e c 1997
Dynamics of Viscoplastic Deformation in Amorphous Solids
M.L.Falk and https://www.doczj.com/doc/483454190.html,nger
Department of Physics,University of California,Santa Barbara,CA 93106
(February 1,2008)
We propose a dynamical theory of low-temperature shear deformation in amorphous solids.Our analysis is based on molecular-dynamics simulations of a two-dimensional,two-component noncrys-talline system.These numerical simulations reveal behavior typical of metallic glasses and other viscoplastic materials,speci?cally,reversible elastic deformation at small applied stresses,irreversible plastic deformation at larger stresses,a stress threshold above which unbounded plastic ?ow occurs,and a strong dependence of the state of the system on the history of past deformations.Micro-scopic observations suggest that a dynamically complete description of the macroscopic state of this deforming body requires specifying,in addition to stress and strain,certain average features of a population of two-state shear transformation zones.Our introduction of these new state variables into the constitutive equations for this system is an extension of earlier models of creep in metallic glasses.In the treatment presented here,we specialize to temperatures far below the glass transition,and postulate that irreversible motions are governed by local entropic ?uctuations in the volumes of the transformation zones.In most respects,our theory is in good quantitative agreement with the rich variety of phenomena seen in the simulations.
I.INTRODUCTION
This paper is a preliminary report on a molecular-dynamics investigation of viscoplastic deformation in a non-crystalline solid.It is preliminary in the sense that we have completed only the initial stages of our planned simulation project.The results,however,have led us to a theoretical interpretation that we believe is potentially useful as a guide for further investigations along these lines.In what follows,we describe both the simulations and the theory.
Our original motivation for this project was an inter-est in the physics of deformations near the tips of rapidly advancing cracks,where materials are subject to very large stresses and experience very high strain rates.Un-derstanding the dissipative dynamics which occur in the vicinity of the crack tip is necessary to construct a sat-isfactory theory of dynamic fracture.[1]Indeed,we be-lieve that the problem of dynamic fracture cannot be separated from the problem of understanding the condi-tions under which a solid behaves in a brittle or ductile manner.[2–6]To undertake such a project we eventually shall need sharper de?nitions of the terms “brittle”and “ductile”than are presently available;but we leave such questions to future investigations while we focus on the speci?cs of deformation in the absence of a crack.
We have chosen to study amorphous materials because the best experiments on dynamic instabilities in fracture have been carried out in silica glasses and polymers.[7,8]We know that amorphous materials exhibit both brittle and ductile behavior,often in ways that,on a macro-scopic level,look very similar to deformation in crystals.[9]More generally,we are looking for fundamental prin-ciples that might point us toward theories of deformation and failure in broad classes of macroscopically isotropic solids where thinking of deformation in terms of the dy-namics of individual dislocations [2,3]is either suspect,
due to the absence of underlying crystalline order,or sim-ply intractable,due to the extreme complexity of such an undertaking.In this way we hope that the ideas pre-sented here will be generalizable perhaps to some poly-crystalline materials or even single crystals with large numbers of randomly distributed dislocations.
We describe our numerical experiments in Section II.Our working material is a two-dimensional,two-component,noncrystalline solid in which the molecules interact via Lennard-Jones forces.We purposely main-tain our system at a temperature very far below the glass transition.In the experiments,we subject this material to various sequences of pure shear stresses,during which we measure the mechanical response.The simulations re-veal a rich variety of behaviors typical of metallic glasses [10–13]and other viscoplastic solids,[14]speci?cally:re-versible elastic deformation at small applied stresses,irre-versible plastic deformation at somewhat larger stresses,a stress threshold above which unbounded plastic ?ow occurs,and a strong dependence of the state of the sys-tem on the history of past deformations.In addition,the molecular-dynamics method permits us to see what each molecule is doing at all times;thus,we can identify the places where irreversible molecular rearrangements are occurring.
Our microscopic observations suggest that a dynam-ically complete description of the macroscopic state of this deforming body requires specifying,in addition to stress and strain,certain average features of a popula-tion of what we shall call “shear transformation zones.”These zones are small regions,perhaps consisting of only ?ve or ten molecules,in special con?gurations that are particularly susceptible to inelastic rearrangements in re-sponse to shear stresses.We argue that the constitutive relations for a system of this kind must include equa-tions of motion for the density and internal states of these zones;that is,we must add new time-dependent
state variables to the dynamical description of this sys-tem.[15,16]Our picture of shear transformation zones is based on earlier versions of the same idea due to Argon, Spaepen and others who described creep in metallic alloys in terms of activated transitions in intrinsically heteroge-neous materials.[17–22]These theories,in turn,drew on previous free-volume formulations of the glass transition by Turnbull,Cohen and others in relating the transition rates to local free-volume?uctuations.[20,23–25]None of those theories,however,were meant to describe the low-temperature behavior seen here,especially the di?erent kinds of irreversible deformations that occur below and above a stress threshold,and the history dependence of the response of the system to applied loads.
We present theory of the dynamics of shear transfor-mation zones in Section III.This theory contains four crucial features that are not,so far as we know,in any previous analysis:First,once a zone has transformed and relieved a certain amount of shear stress,it cannot transform again in the same direction.Thus,the system saturates and,in the language of granular materials,it becomes“jammed.”Second,zones can be created and destroyed at rates proportional to the rate of irreversible plastic work being done on the system.This is the ingre-dient that produces a threshold for plastic?ow;the sys-tem can become“unjammed”when new zones are being created as fast as existing zones are being transformed. Third,the attempt frequency is tied to the noise in the system,which is driven by the strain rate.The stochastic nature of these?uctuations is assumed to arise from ran-dom motions associated with the disorder in the system. And,fourth,the transition rates are strongly sensitive to the applied stress.It is this sensitivity that produces memory e?ects.
The resulting theory accounts for many of the features of the deformation dynamics seen in our simulations. However,it is a mean?eld theory which fails to take into account any spatial correlations induced by interac-tions between zones,and therefore it cannot explain all aspects of the behavior that we observe.In particular, the mean-?eld nature of our theory precludes,at least for the moment,any analysis of strain localization or shear banding.
II.MOLECULAR-DYNAMICS EXPERIMENTS
A.Algorithm
Our numerical simulations have been performed in the spirit of previous investigations of deformation in amor-phous solids[26–29].We have examined the response to an applied shear of a noncrystalline,two-dimensional, two-component solid composed of either10,000or20,000 molecules interacting via Lennard-Jones forces.Our molecular dynamics(MD)algorithm is derived from a standard“NPT”dynamics scheme[30],i.e.a pressure-temperature ensemble,with a Nose-Hoover thermostat, [31–33]and a Parinello-Rahman barostat[34,35]modi-?ed to allow imposition of an arbitrary two-dimensional stress tensor.The system obeys periodic boundary con-ditions,and both the thermostat and barostat act uni-formly throughout the sample.
Our equations of motion are the following:
˙r n=
p n
τ2
T
(
T kin
τ2P
V
4V n
m F i nm r j nm,(2.6)
where F i nm is the i’th component of the force between particles n and m;r j nm is the j’th component of the vec-tor displacement between those particles;and V is the volume of the system.L is the locus of points which de-scribe the boundary of the simulation cell.While(2.5) is not directly relevant to the dynamics of the particles, keeping track of the boundary is necessary in order to properly calculate intermolecular distances in the peri-odic cell.
The additional dynamical degrees of freedom in(2.1-2.5)are a viscosityξ,which couples the system to the thermal reservoir,and a strain rate,[˙ε]via which the externally applied stress is transmitted to the system. Note that[˙ε]induces an a?ne transformation about a reference point R0which,without loss of generality,we choose to be the origin of our coordinate system.In a conventional formulation,[σ]would be equal to?P[I], where P is the pressure and[I]is the unit tensor.In that case,these equations of motion are known to produce the same time-averaged equations of state as an equilibrium NPT ensemble.[30]By instead controlling the tensor[σ], including its o?-diagonal terms,it is possible to apply a shear stress to the system without creating any preferred surfaces which might enhance system-size e?ects and in-terfere with observations of bulk properties.The applied stress and the strain-rate tensor are constrained to be
symmetric in order to avoid physically uninteresting ro-tations of the cell.Except where otherwise noted,all of our numerical experiments are carried out at constant temperature,with P =0,and with the sample loaded in uniform,pure shear.
We have chosen the arti?cial time constants τT and τP to represent physical aspects
of the system.As suggested by Nose [31],τT is the time for a sound wave to travel an interatomic distance and,as suggested by Anderson [36],τP is the time for sound to travel the size of the system.
B.Model Solid
The special two-component system that we have cho-sen to study here has been the subject of other investiga-tions [37–39]primarily because it has a quasi-crystalline
ground state.The important point for our purposes,however,is that this system can be quenched easily into an apparently stable glassy state.Whether this is ac-tually a thermodynamically stable glass phase is of no special interest here.We care only that the noncrys-talline state has a lifetime that is very much longer than the duration of our experiments.
Our system consists of molecules of two di?erent sizes,which we call “small”(S )and “large”(L ).The interac-tions between these molecules are standard 6-12Lennard-Jones potentials:
U αβ(r )=4e αβ
a αβ
r 6 (2.7)where the subscripts α,βdenote S or L .We choose the zero-energy interatomic distances,a αβ,to be a SS =2sin(
π
5),
a SL =1;(2.8)
with bond strengths:
e SL =1,
e SS =e LL =
1
N S =1+√4
.(2.10)
In the resulting system,it is energetically favorable for ten small molecules to surround one large molecule,or for ?ve large molecules to surround one small molecule.The highly frustrated nature of this system avoids problems of local crystallization that often occur in two dimensions where the nucleation of single component crystalline re-gions is di?cult to avoid.As shown by Lan?c on et al [37],this system goes through something like a glass transition upon cooling from its liquid state.The glass transition temperature is 0.3T 0where k B T 0=e SL .All the simula-tions reported here have been carried out at a tempera-ture T =0.001T 0,that is,at 0.3%of the glass transition temperature.Thus,all of the phenomena to be discussed here take place at a temperature very much lower than the energies associated with the molecular interactions.In order to start with a densely packed material,we have created our experimental systems by equilibrating a random distribution of particles under high pressure at the low temperature mentioned above.After allowing the system to relax at high pressure,we have reduced the pressure to zero and again allowed the sample to relax.Our molecular dynamics procedure permits us to relax the system only for times of order nanoseconds,which are not long enough for the material to experience any signi?cant amount of annealing,especially at such a low temperature.
We have performed numerical experiments on two dif-ferent samples,containing 10,000and 20,000molecules respectively.All of the simulation results shown are from the larger of the two samples;the smaller sample has been used primarily to check the reliablility of our procedures.We have created each of these samples only once;thus each experiment using either of them starts with precisely the same set of molecules in precisely the same positions.As will become clear,there are both advantages and un-certainties associated with this procedure.On the one hand,we have a very carefully controlled starting point for each experiment.On the other hand,we do not know how sensitive the mechanical properties of our system
Shear Modulus
2D Poisson Ratio
Sample 1
10,000
31
30
16
0.57
TABLE I.Sample Sizes and Elastic Constants
might be to details of the preparation process,nor do we know whether to expect signi?cant sample-to-sample variations in the molecular con?gurations.To illustrate these uncertainties,we show the elastic constants of the samples in Table 1.The moduli are expressed there in units of e SL /a 2SL .(Note that the Poisson ratio for a two-dimensional system has an upper bound of 1rather than 0.5as in the three-dimensional case.)The appreciable di?erences between the moduli of supposedly identical materials tell us that we must be very careful in drawing detailed conclusions from these preliminary results.
C.Simulation Results:Macroscopic Observations
In all of our numerical experiments,we have tried sim-ply to mimic conventional laboratory measurements of viscoplastic properties of real materials.The ?rst of these is a measurement of stress at constant strain rate.As we shall see,this supposedly simplest of the experiments is especially interesting and problematic for us because it necessarily probes time-dependent behavior near the plastic yield stress.
Our
results,for two di?erent strain rates,are shown in Figure 1.The strain rates are expressed in units propor-tional to the frequency of oscillation about the minimum in the Lennard-Jones potential,speci?cally,in units of
ω0≡(e SL /ma 2SL )
1
2
.
Time
0.01.0
2.0
3.0
%S h e a r S t r a i n
S t r e s s
FIG.2.Shear strain (open symbols)vs.time for sev-eral applied shear stresses (solid symbols).The stresses
have been ramped up at a constant rate until reaching a maximum value and then have been held constant.The strain and stress axes are related by twice the shear modu-lus so that,for linear elastic response,the open and closed symbols would be coincident.For low stresses the sample responds in an almost entirely elastic manner.For inter-mediate stresses the sample undergoes some plastic defor-mation prior to jamming.In the case where the stress is brought above the yield stress,the sample deforms indef-initely.Time is measured in units of (ma 2SL /e SL )
1
2
.The stresses and strain axes are related by twice the shear modulus so that,if the response is linearly elastic,the two curves lie on on top of one an-other.In the case labelled (△),the ?nal stress is small,and the response is nearly elastic.For cases (?)and (2),the sample deforms plastically until it reaches some ?nal strain,at which it ceases to undergo further deformation
100.0200.0
300.0400.0
Time
0.00.5
1.0
1.5
%S t r a i n
%Shear Strain
0.000.10
0.20
0.30
0.40
S t r e s s
Shear Stress
%Dilational Strain
FIG.3.Stress and strain vs.time for one particular loading where the stress has been ramped up to σs =0.25,held for a time,and then released.Note that,in addi-tion to the shear response,the material undergoes a small amount of dilation.
0.0
100.0200.0
300.0400.0500.0
Time
0.00.2
0.4
0.6
0.8
1.0
%S h e a r S t r a i n
Elastic Strain Inelastic Strain
FIG.4.Elastic and inelastic strain vs time for the same simulation as that shown in Figure 3.The inelastic strain is found by subtracting the linearly elastic strain from the total strain.Note the partial recovery of the in-elastic portion of the strain which occurs during and after unloading.
on observable timescales.(We cannot rule out the possi-bility of slow creep at much longer times.)In case (3),for which the ?nal stress is the largest of the three cases shown,the sample continues to deform plastically at con-stant stress throughout the duration of the experiment.We conclude from these and a number of similar experi-mental runs that there exists a well de?ned critical stress for this material,below which it reaches a limit of plastic deformation,that is,it “jams,”and above which it ?ows plastically.Because the stress is ramped up quickly,we can see in curves (2)and (3)of Figure 2that there is a separation of time scales between the elastic and plastic
responses.The elastic response is instantaneous,while the plastic response develops over a few hundred molec-ular vibrational periods.To see the distinction between these behaviors more clearly,we have performed experi-ments in which we load the system to a ?xed,subcritical stress,hold it there,and then unload it by ramping the stress back down to zero.In Figure 3,we show this stress and the resulting total shear strain,as functions of time,for one of those experiments.If we de?ne the the elas-tic strain to be the stress divided by twice the previously measured,as-quenched,shear modulus,then we can com-pute the inelastic strain by subtracting the elastic from the total.The result is shown in Figure 4.Note that most,but not quite all,of the inelastic strain consists of nonrecoverable plastic deformation that persists after unloading to zero stress.Note also,as shown in Fig-ure 3,that the system undergoes a small dilation during this process,and that this dilation appears to have both elastic and inelastic components.
Using the simple prescription outlined above,we have measured the ?nal inelastic shear strain as a function of shear stress.That is,we have measured the shear strain once the system has ceased to deform as in the subcritical cases in Figure 2,and then subtracted the elastic part.The results are shown in Fig.5.As expected,we see only very small amounts of inelastic strain at low stress.As the stress approaches the yield stress,the inelastic strain appears to diverge approximately logarithmically.
The ?nal test that we have performed is to cycle the system through loading,reloading,and reverse-loading.As shown in Figure 6,the sample is ?rst loaded on the curve from a to b .The initial response is linearly elas-tic,but,eventually,deviation from linearity occurs as the material begins to deform inelastically.From b to c ,the stress is constant and the sample continues to de-form inelastically until reaching a ?nal strain at c .Upon unloading,from c to d ,the system does not behave in a purely elastic manner but,rather,recovers some por-tion of the strain anelastically.While held at zero stress,the sample continues to undergo anelastic strain recovery from d to e .
When the sample is then reloaded from e to f ,it un-dergoes much less inelastic deformation than during the initial loading.From f to g the sample again deforms inelastically,but by an amount only slightly more than the previously recovered strain,returning approximately to point c .Upon unloading again from g to h to i ,less strain is recovered than in the previous unloading from c through e .
It is during reverse loading from i to k that it becomes apparent that the deformation history has rendered the amorphous sample highly anisotropic in its response to further applied shear.The inelastic strain from i to k is much greater than that from e to g ,demonstrating a very signi?cant Bauschinger e?ect.The plastic defor-mation in the initial direction apparently has biased the sample in such a way as to inhibit further inelastic yield
0.00
0.100.200.300.40
Shear Stress
0.02.0
4.0
6.0
%F i n a l I n e l a s t i c S h e a r S t r a i n
FIG.5.Final inelastic strain vs.applied stress for stresses below yield.The simulation data (squares)have been obtained by running the simulations until all defor-mation apparently had stopped.The comparison to the theory (line)was obtained by numerically integrating the equations of motion for a period of 800time units,the duration of the longest simulation runs.
?1.0
0.0 1.0
%Shear Strain
?0.2
0.0
0.2
S h e a r S t r e s s
700
1400
Time
?0.4
0.00.4S h e a r S t r e s s
a
b c
d
e
f
g
h
i
j
a
k
b
c d e f g
h
i
j
k
FIG. 6.Stress-strain trajectory for a molecular-dynamics experiment in which the sample has been
loaded,unloaded,reloaded,unloaded again,and then re-verse-loaded,all at stresses below the yield stress.The smaller graph above shows the history of applied shear stress with letters indicating identical times in the two graphs.The dashed line in the main graph is the theo-retical prediction for the same sequence of stresses.Note that a small amount of inelastic strain recovery occurs af-ter the ?rst unloading in the simulation,but that no such behavior occurs in the theory.Thus,the theoretical curve from c though h unloads,reloads and unloads again all along the same line.
in the same direction,but there is no such inhibition in the reverse direction.The material,therefore,must in some way have microstructurally encoded,i.e.partially “memorized,”its loading history.
D.Simulation Results:Microscopic Observations
Our numerical methods allow us to examine what is happening at the molecular level during these deforma-tions.To do this systematically,we need to identify where irreversible plastic rearrangements are occurring.More precisely,we must identify places where the molec-ular displacements are non-a?ne,that is,where they de-viate substantially from displacements which can be de-scribed by a linear strain ?eld.Our mathematical tech-nique for identifying regions of non-a?ne displacement has been described by one of us (MLF)in an earlier pub-lication.[40]For completeness,we repeat it here.
We start with a set of molecular positions and sub-sequent displacements,and compute the closest possible approximation to a local strain tensor in the neighbor-hood of any particular molecule.To de?ne that neigh-borhood,we de?ne a sampling radius,which we choose to be the interaction range,2.5a SL .The local strain is then determined by minimizing the mean square di?er-ence between the the actual displacements of the neigh-boring molecules relative to the central one,and the rel-ative displacements that they would have if they were in a region of uniform strain εij .That is,we de?ne
D 2
(t,?t )=
n
i
r i n (t )?r i 0(t )? j
(δij +εij ) r j
n (t ??t )?r j 0(t ??t )
2,(2.11)
where the indices i and j denote spatial coordinates,and
the index n runs over the molecules within the interac-tion range of the reference molecule,n =0being the
reference molecule.r i
n (t )is the i ’th component of the position of the n ’th molecule at time t .We then ?nd the εij which minimizes D 2by calculating:
X ij =
n
(r i n (t )?r i 0(t ))×
(r j n (t ??t )?r j 0(t ??t )),(2.12)
Y ij =
n
(r i n (t ??t )?r i 0(t ??t ))×(r j n (t ??t )?r j 0(t ??t )),(2.13)εij =
k
X ik Y ?1jk ?δij .
(2.14)
The minimum value of D 2(t,?t )is then the local de-viation from a?ne deformation during the time interval
[t ??t,t ].We shall refer to this quantity as D 2
min .
(a)(b)
(c)(d)
FIG.7.Intensity plots of D2min,the deviation from a?ne deformation,for various intervals during two simu-lations.Figures(a),(b)and(c)show deformation during one simulation in which the stress has been ramped up quickly to a value less than the yield stress and then held constant.Figure(a)shows deformations over the?rst 10time units,and?gure(b)over the?rst30time units. Figure(c)shows the same state as in(b),but with D2min computed only for deformations that took place during the preceeding1time unit.In Figure(d),the initial sys-tem and the time interval(10units)are the same as in (a),but the stress has been applied in the opposite direc-tion.The gray scale in these?gures has been selected so that the darkest spots identify molecules for which |D min|≈0.5a SL
.
FIG.8.Close-up picture of a shear transformation zone before and after undergoing transformation.Molecules af-ter transformation are shaded according to their values of D2min using the same gray scale as in Figure7.The di-rection of the externally applied shear stress is shown by the arrows.The ovals are included solely as guides for the eye.
We have found that D2min is an excellent diagnostic for
identifying local irreversible shear transformations.Fig-ure7contains four di?erent intensity plots of D2min for a
particular system as it is undergoing plastic deformation. The stress has been ramped up to|σs|=0.12in the time interval[0,12]and then held constant in an experiment analogous to that shown in Figure2.Figure7(a)shows
D2min for t=10,?t=10.It demonstrates that the non-a?ne deformations occur as isolated small events.In(b) we observe the same simulation,but for t=30,?t=30; that is,we are looking at a later time,but again we con-sider rearrangements relative to the inital con?guration. Now it appears that the regions of rearrangement have a larger scale structure.The pattern seen here looks like an incipient shear band.However,in(c),where t=30,?t=1,we again consider this later time but look only at rearrangements that have occurred in the preceeding short time interval.The events shown in this?gure are small,demonstrating that the pattern shown in(b)is, in fact,an aggregation of many local https://www.doczj.com/doc/483454190.html,stly,in (d),we show an experiment similar in all respects to(a) except that the sign of the stress has been reversed.As in(a),t=10,?t=10,and again we observe small isolated events.However,these events occur in di?erent locations,implying a direction dependence of the local transformation mechanism.
Next we look at these processes in yet more detail. Figure8is a close-up of the molecular con?gurations in the lower left-hand part of the largest dark cluster seen in Figure7(c),shown just before and just after a shear transformation.During this event,the cluster of one large and three small molecules has compressed along the top-left/bottom-right axis and extended along the bottom-left/top-right axis.This deformation is consis-tent with the orientation of the applied shear,which is in the direction shown by the arrows on the outside of the ?gure.Note that this rearrangement takes place without signi?cantly a?ecting the relative positions of molecules in the immediate environment of the transforming region. This is the type of rearrangement that Spaepen identi?es as a“?ow defect.”[20]As mentioned in the introduction, we shall call these regions“shear transformation zones.”
III.THEORETICAL INTERPRETATION OF THE MOLECULAR-DYNAMICS EXPERIMENTS
A.Basic Hypotheses
We turn now to our attempts to develop a theoretical interpretation of the phenomena seen in the simulations. We shall not insist that our theory reproduce every detail of these results.In fact,the simulations are not yet com-plete enough to tell us whether some of our observations are truly general properties of the model or are artifacts of the ways in which we have prepared the system and carried out the numerical experiments.Our strategy will
be,?rst,to specify what we believe to be the basic frame-work of a theory,and then to determine which speci?c assumptions within this framework are consistent with the numerical experiments.
There are several features of our numerical experi-ments that we shall assume are fundamentally correct and which,therefore,must be outcomes of our theory. These are:(1)At a su?ciently small,?xed load,i.e.un-der a constant shear stress less than some value that we identify as a yield stress,the system undergoes a?nite plastic deformation.The amount of this deformation di-verges as the loading stress approaches the yield stress.
(2)At loading stresses above the yield stress,the system ?ows visco-plastically.(3)The response of the system to loading is history-dependent.If it is loaded,unloaded, and then reloaded to the same stress,it behaves almost elastically during the reloading,i.e.it does not undergo additional plastic deformation.On the other hand,if it is loaded,unloaded,and then reloaded with a stress of the opposite sign,it deforms substantially in the opposite direction.
Our theory consists of a set of rate equations describ-ing plastic deformation.These include an equation for the inelastic strain rate as a function of the stress plus other variables that describe the internal state of the sys-tem.We also postulate equations of motion for these state variables.Deformation theories of this type are in the spirit of investigations by E.Hart[15]who,to the best of our knowledge,was the?rst to argue in a math-ematically systematic way that any satisfactory theory of plasticity must include dynamical state variables,be-yond just stress and strain.A similar point of view has been stressed by Rice.[16]Our analysis is also in?uenced by the use of state variables in theories of friction pro-posed recently by Ruina,Dieterich,Carlson,and others. [41–46]
Our picture of what is happening at the molecular level in these systems is an extension of the ideas of Turnbull, Cohen,Argon,Spaepen and others.[17–21,23–25]These authors postulated that deformation in amorphous mate-rials occurs at special sites where the molecules are able to rearrange themselves in response to applied stresses. As described in the preceding chapter,we do see such sites in our simulations,and shall use these shear trans-formation zones as the basis for our analysis.However, we must be careful to state as precisely as possible our de?nition of these zones,because we shall use them in ways that were not considered by the previous authors. One of the most fundamental di?erences between pre-vious work and ours is the fact that our system is ef-fectively at zero temperature.When it is in mechanical equilibrium,no changes occur in its internal state be-cause there is no thermal noise to drive such changes. Thus the shear transformation zones can undergo tran-sitions only when the system is in motion.Because the system is strongly disordered,the forces induced by large-scale motions at the position of any individual molecule may be noisy.These?uctuating forces may even look as if they have a thermal component.[47]The thermody-namic analogy(thermal activation of shear transforma-tions with temperature being some function of the shear rate)may be an alternative to(or an equivalent of)the theory to be discussed here.However,it is beyond the scope of the present investigation.
Our next hypothesis is that shear transformation zones are geometrically identi?able regions in an amorphous solid.That is,we assume that we could—at least in principle—look at a picture of any one of the computer-generated states of our system and identify small regions that are particularly susceptible to inelastic rearrange-ment.As suggested by Fig.8,these zones might con-sist of groups of four or more relatively loosely bound molecules surrounded by more rigid“cages.”But that speci?c picture is not necessary.The main idea is that some such irregularities are locked in on time scales that are very much longer than molecular collision times. That is not to say that these zones are permanent fea-tures of the system on experimental time scales.On the contrary,the tendency of these zones to appear and dis-appear during plastic deformation will be an essential ingredient of our theory.
We suppose further that these shear transformation zones are two-state systems.That is,in the absence of any deformation of the cage of molecules that surrounds them,they are equally stable in either of two con?gu-rations.Very roughly speaking,the molecular arrange-ments in these two con?gurations are elongated along one or the other of two perpendicular directions which, shortly,we shall take to be coincident with the principal axes of the applied shear stress.The transition between one such state and the other constitutes an elementary in-crement of shear strain.Note that bistability is the natu-ral assumption here.More than two states of comparable stability might be possible but would have relatively low probability.A crucial feature of these bistable systems is that they can transform back and forth between their two states but cannot make repeated transformations in one direction.Thus there is a natural limit to how much shear can take place at one of these zones so long as the zone remains intact.
We now consider an ensemble of shear transformation zones and estimate the probability that any one of them will undergo a transition at an applied shear stressσs. Because the temperatures at which we are working are so low that ordinary thermal activation is irrelevant,we focus our attention on entropic variations of the local free volume.Our basic assumption is that the transition probability is proportional to the probability that the molecules in a zone have a su?ciently large excess free volume,say?V?,in which to rearrange themselves.This critical free volume must depend on the magnitude and orientation of the elastic deformation of the zone that is caused by the externally applied stress,σs.
At this point,our analysis borrows in its general ap-proach,but not in its speci?cs,from recent developments in the theory of granular materials[48]where the only
extensive state variable is the volume ?.What follows is a very simple approximation which,at great loss of gen-erality,leads us quickly to the result that we need.The free volume,i.e.the volume in excess of close packing that the particles have available for motion,is roughly
??N v 0≡N v f ,
(3.1)
where N is the total number of particles,v f is the av-erage free volume per particle,and v 0is the volume per particle in an ideal state of random dense packing.In the dense solids of interest to us here,v f ?v 0,and there-fore v 0is approximately the average volume per particle even when the system is slightly dilated.The number of states available to this system is roughly proportional to (v f /h )N ,where h is an arbitrary constant with di-mensions of volume —the analog of Planck’s constant in classical statistical mechanics —that plays no role other than to provide dimensional consistency.Thus the entropy,de?ned here to be a dimensionless quantity,is
S (?,N )～=N ln
v
f
N h .(3.2)The intensive variable analogous to temperature is χ:
1
??
～=
12μ,
(3.8)
where μis the shear modulus.
In a more general formulation,we shall have to con-sider a distribution of orientations of the shear transfor-mation zones.That distribution will not necessarily be isotropic when plastic deformations are occurring,and very likely the distribution itself will be a dynamical en-tity with its own equations of motion.Our present anal-ysis,however,is too crude to justify any such level of sophistication.
The last of our main hypotheses is an equation of mo-tion for the densities of the shear transformation zones.Denote the two states of the shear transformation zones by the symbols +and ?,and let n ±be the number den-sities of zones in those states.We then write:˙n ±=R ?n ??R ±n ±?C 1(σs ˙εin s )n ±+C 2(σs ˙εin s ).
(3.9)
Here,the R ±are the rates at which ±states transform to ?states.These must be consistent with the transition probabilities described in
the preceding paragraphs.The last two terms in (3.9)describe the way in which the population of shear transformation zones changes as the system undergoes plastic deformation.The zones can be annihilated and created —as shown by the terms with coe?cients C 1and C 2respectively —at rates pro-portional to the rate σs ˙εin s at which irreversible work is being done on the system.This last assumption is simple
and plausible,but it is not strictly dictated by the physics
in any way that we can see.A caveat:In certain circum-stances,when the sample does work on its environment,σs˙εin s could be negative,in which case the annihilation and creation terms in(3.9)could produce results which would not be physically plausible.We believe that such states in our theory are dynamically accessible only from unphysical starting con?gurations.In related theories, however,that may not be the case.
It is important to recognize that the annihilation and creation terms in(3.9)are interaction terms,and that they have been introduced here in a mean-?eld approx-imation.That is,we implicitly assume that the rates at which shear transformation zones are annihilated and created depend only on the rate at which irreversible work is being done on the system as a whole,and that there is no correlation between the position at which the work is being done and the place where the annihilation or creation is occurring.This is in fact not the case as shown by Fig.7(b),and is possibly the weakest aspect of our theory.
With the preceding de?nitions,the time rate of change of the inelastic shear strain,˙εin s,has the form:
˙εin s=V z?ε[R+n+?R?n?],(3.10) where V z is the typical volume of a zone and?εis the increment of local shear strain.
B.Speci?c Assumptions
We turn now to the more detailed assumptions and analyses that we need in order to develop our general hypotheses into a testable theory.
According to our hypothesis about the probabilities of volume?uctuations,we should write the transition rates in(3.9)in the form:
R±=R0exp ??V?(±σs)
2 exp
??V?(σs)v
f
;
S(σs)≡1v
f
?exp ??V?(?σs)
V z?ε 1?σs n?
V z?εˉσ 1?n tot
V z?εn∞ˉσ
;C2≡1
undergoing a?ne strain.If we assume that these devia-
tions are di?usive,and that the a?ne deformation over some time interval scales like the strain rate,then the
non-a?ne transformation rate must scale like the square root of the a?ne rate.(Di?usive deviations from smooth
trajectories have been observed directly in numerical sim-ulations of sheared foams,[47]but only in the equivalent
of our plastic?ow regime.)In(3.18),we further assume that the elastic and inelastic strain rates are incoherent,
and thus write the sum of squares within the brackets. In what follows,we shall not be able to test the valid-
ity of(3.18)with any precision.Most probably,the only properties of importance to us for present purposes are
the magnitude of R0and the fact that it vanishes when the shear rates vanish.
Finally,we need to specify the ingredients of?V?and v f.For?V?,we choose the simple form:
?V?(σs)=V?0exp(?σs/ˉμ)(3.19) where V?0is a volume,perhaps of order the average
molecular volume v0,andˉμhas the dimensions of a shear modulus.The right-hand side of(3.19)simply re?ects
the fact that the free volume needed for an activated transition will decrease if the zone in question is loaded
with a stress which coincides with the direction of the resulting strain.We choose the exponential rather than
a linear dependence because it makes no sense for the incremental free volume V?0to be negative,even for very
large values of the applied stresses.
Irreversibility enters the theory via a simple switching
behavior that occurs when theσs-dependence of?V?in (3.19)is so strong that it converts a negligably small rate
atσs=0to a large rate at relevant,non-zero values of σs.If this happens,then zones that have switched in one
direction under the in?uence of the stress will remain in that state when the stress is removed.
In the formulation presented here,we consider v f to be constant.This is certainly an approximation;in fact,
as seen in Figure3,the system dilates during shear de-formation.We have experimented with versions of this
theory in which the dilation plays a controlling role in
the dynamics via variations in v f.We shall not discuss these versions further because they behaved in ways that
were qualitatively di?erent from what we observed in our simulations.The di?erences arise from feedback between
inelastic dilation and?ow which occur in these dilational models,and apparently not in the simulations.A sim-
ple comparison of the quantities involved demonstrates that the assumption that v f is approximately constant
is consistent with our other assumptions.If we assume that the increment in free volume at zero stress must be
of order the volume of a small particle,V?0≈v0≈0.3, and then look ahead and use our best-?t value for the
ratio V?0/v f≈14.0(see Section III D,Table II),we ?nd v f≈0.02.Since the change in free volume due to a dilational strainεd is?v f=εd/ρ,whereρis the number density,andεd<0.2%for all shear stresses ex-
cept those very close to yield,it appears that,generally,?v f≈εd v0?v f.Even whenεd=1%,the value observed in our simulations at yield,the dilational free volume is only about the same as the initial free volume estimated by this analysis.
As a?nal step in examining the underlying structure of these equations of motion,we make the following scaling transformations:
2μεin s
n∞≡?;
n tot
ˉσ≡Σ.(3.20) Then we?nd:
˙E=ˉE F(Σ,Λ,?);(3.21)˙?=2F(Σ,Λ,?)(1?Σ?);(3.22)
˙Λ=2F(Σ,Λ,?)Σ(1?Λ);(3.23) where
F(Σ,Λ,?)=R0[ΛS(Σ)??C(Σ)];(3.24) and:
C(Σ)=1v
f
e?AΣ)+exp(?
V?0
2 exp(?V?0v f e AΣ)
.(3.25) Here,
A≡
ˉσ
ˉσ
.(3.26) The rate factor in(3.18)can be rewritten:
R0=?ν14,(3.27) where
?ν≡
ˉσ
?=Λ
S (Σ)
v f
sinh(A Σ) ?1
.
(3.30)
Now suppose that,instead of increasing the stress at a ?nite rate as we have done in our numerical experiments,we let it jump discontinuously —from zero,perhaps —to its value Σat time t =0.While Σis constant,(3.22)and (3.23)can be solved to yield:
1?Λ(t )
1?Σ?(0)
,
(3.31)
where Λ(0)and ?(0)denote the initial values of Λ(t )and ?(t )respectively.Similarly,we can solve (3.21)and (3.22)for E (t )in terms of ?(t )and obtain a relationship between the bias in the population of defects and the change in strain,
E (t )=E (0)+ˉE
1?Σ?(t ) .(3.32)
Combining (3.29),(3.31)and (3.32),we can determine the change in strain prior to jamming.That is,for Σsu?ciently small that the following limit exists,we can compute a ?nal inelastic strain E f :
E f ≡lim t →∞
E (t )=
E (0)+
ˉE
1?ΣT (Σ)
.(3.33)
The right-hand side of (3.33),for E (0)=?(0)=0,
should be at least a rough approximation for the inelastic strain as a function of stress as shown in Figure 5.
The preceding analysis is our mathematical descrip-tion of how the system jams due to the two-state nature of the shear transformation zones.Each increment of plastic deformation corresponds to the transformation of zones aligned favorably with the applied shear stress.As the zones transform,the bias in their population —i.e.?—grows.Eventually,all of the favorably aligned zones that can transform at the given magnitude and direction of the stress have undergone their one allowed transfor-mation,?has become large enough to cause F in (3.24)to vanish,and plastic deformation comes to a halt.
The second steady-state is a plastically ?owing solu-tion in which ˙E =0but ˙?
=˙Λ=0.From (3.22)and (3.23)we see that this condition requires:
?=
1
Σ
C (Σ) 2
.
(3.35)
This ?owing solution arises from the non-linear annihi-lation and creation terms in (3.9).In the ?owing state,stresses are high enough that shear transformation zones are continuously created.A balance between the rate of zone creation and the rate of transformation determines the rate of deformation.
Examination of (3.22)and (3.23)reveals that the jammed solution (3.29)is stable for low stresses,while the ?owing solution (3.34)is stable for high stresses.The crossover between the two solutions occurs when both (3.29)and (3.34)are satis?ed.This crossover de?nes the yield stress Σy ,which satis?es the condition
1
Value 0.32 5.7% 50.0 14.0 0.25 2.0
100
200
300400500
Time
0.0
0.5
1.0
1.5
2.0
2.5
%S h e a r S t r a i
n
FIG.9.Strain vs.time for simulations in which the stress has been ramped up at a controlled rate to stresses of 0.1,0.2and 0.3,held constant,and then ramped down to zero (solid lines).The dashed lines are the correspond-ing theoretical predictions.
stresses have stopped changing.Our theory seems to rule out any such recovery of inelastic strain at zero stress;thus we cannot account for this phenomenon except to remark that it must have something to do with the ini-tial state of the as-quenched system.As seen in Figure 6,no such recovery occurs when the system is loaded and unloaded a second time.
In Figure 6,we compare the stress-strain hysteresis loop in the simulation (solid line)with that predicted by the theory (dashed line).Apart from the inelastic strain recovery after the ?rst unloading in the simulation,the theory and the experiment agree well with one another at least through the reverse loading to point k .The agreement becomes less good in subsequent cycles of the hysteresis loop,possibly because shear bands are forming during repeated plastic deformations.
In the last of the tests of theory to be reported here,we have added in Figure 1two theoretical curves for stresses as functions of strain at the two di?erent constant strain rates used in the simulations.The agreement between theory and experiment is better than we probably should expect for situations in which the stresses necessarily rise to values at or above the yield stress.Moreover,the va-lidity of the comparison is obscured by the large ?uctu-ations in the data,which we believe to be due primarily to small sample size.
Among the interesting features of the theoretical re-sults in Figure 1are the peaks in the stresses that occur just prior to the establishment of steady-states at con-stant stresses.These peaks occur because the internal degrees of freedom of the system,speci?cally ?(t )and Λ(t ),cannot initially equilibrate fast enough to accomo-date the rapidly increasing inelastic strain.Thus there is a transient sti?ening of the material and a momentary increase in the stress needed to maintain the constant
strain rate.This kind of e?ect may in part be the ex-planation for some of the oscillations in the stress seen in the experiments.In a more speculative vein,we note that this is our ?rst direct hint of the kind of dynamic plastic sti?ening that is needed in order to transmit high stresses to crack tips in brittle fracture.The orders of magnitude of the time scales are even roughly the same.The strain rates used here,and those that occur near the tips of brittle cracks,are both of the order of 107per second.
IV.CONCLUDING REMARKS
The most striking and robust conclusion to emerge from this investigation,in our opinion,is that a wide range of realistic,irreversible,viscoplastic phenomena oc-cur in an extremely simple molecular-dynamics model —a two-dimensional,two-component,Lennard-Jones amorphous solid at essentially zero temperature.An al-most equally striking conclusion is that a theory based on the dynamics of two-state shear transformation zones is in substantial agreement with the observed behavior of this model.This theory has survived several quantitative tests of its applicability.
We stated in our Introduction that this is a preliminary report.Both the numerical simulations and the theoreti-cal analysis require careful evaluation and improvements.Most importantly,the work so far raises many important questions that need to be addressed in future investiga-tions.
The ?rst kind of question pertains to our molecular-dynamics simulations:Are they accurate and repeatable?We believe that they are good enough for present pur-poses,but we recognize that there are potentially impor-tant di?culties.The most obvious of these is that our simulations have been performed with very small sys-tems;thus,size e?ects may be important.For example,the fact that only a few shear transforming regions are active at any time may account for abrupt jumps and other irregularities sometimes seen in the simulations,e.g.in Figure 1.We have performed the simulations in a periodic cell to eliminate edge e?ects.We also have tried to compare results from two systems of di?erent sizes,although only the results from the larger system are presented here.Unfortunately,comparisons between any two di?erent initial con?gurations are di?cult be-cause of our inability,as yet,to create reproduceable glassy starting con?gurations (a problem which we shall discuss next).However,we have seen qualitatively the same behavior in both systems,and assume that phe-nomena which are common to both systems can be used as a guide for theoretical investigations.
As noted in Section IIB and in Table ,our two systems had quite di?erent elastic moduli.(Remarkably,their yield stresses were nearly identical.It would be interest-ing to learn whether this is a repeatable and/or physically
important phenomenon.)The discrepancy between the elastic properties of the two systems leads us to believe that,in future work,we shall have to learn how to con-trol the initial con?gurations more carefully,perhaps by annealing the systems after the initial quenches.Unfor-tunately,straightforward annealing at temperatures well below the glass transition is not yet possible with stan-dard molecular-dynamics algorithms,which can simulate times only up to about a microsecond for systems of this size even with today’s fastest computers.Monte Carlo techniques or accelerated molecular-dynamics algorithms may eventually be useful in this e?ort.[50–52]An alter-native strategy may be simply to look at larger numbers of simulations.
By far the most di?cult and interesting questions, however,pertain to our theoretical analysis.Although Figures7and8provide strong evidence that irreversible shear transformations are localized events,we have no sharp de?nition of a“shear transformation zone.”So far, we have identi?ed these zones only after the fact,that is, only by observing where the transformations are taking place.Is it possible,at least in principle,to identify zones before they become active?
One ingredient of a better de?nition of shear transfor-mation zones will be a generalization to isotropic amor-phous systems in both two and three dimensions.As we noted in Chapter III,our functions n±(t)should be ten-sor quantities that describe distributions over the ways in which the individual zones are aligned with respect to the orientation of the applied shear stress.We be-lieve that this is a relatively easy generalization;one of us(MLF)expects to report on work along these lines in a later publication.
Our more urgent reason for needing a better under-standing of shear transformation zones is that,with-out such an understanding,we shall not be able to?nd ?rst-principles derivations of several,as-yet purely phe-nomenological,ingredients of our theory.It might be useful,for example,to be able to start from the molecu-lar force constants and calculate the parameters V?0and ˉμthat occur in the activation factor(3.19).These pa-rameters,however,seem to have clear physical interpre-tations;thus we might be satis?ed to deduce them from experiment.In contrast,the conceptually most challeng-ing and important terms are the rate factor in(3.18)and the annihilation and creation terms in(3.9),where we do not even know what the functional forms ought to be. Calculating the rate factor in(3.18),or a correct ver-sion of that equation,is clearly a very fundamental prob-lem in nonequilibrium statistical physics.So far as we know,there are no studies in the literature that might help us compute the force?uctuations induced at some site by externally driven deformations of an amorphous material.Nor do we know how to compute a statisti-cal prefactor analogous,perhaps,to the entropic factor that converts an activation energy to an activation free energy.[49]We do know,however,that that entropic fac-tor will depend strongly on the size and structure of the zone that is undergoing the transformation.
As emphasized in Chapter III,the annihilation and creation terms in(3.9)describe interaction e?ects.Even within the framework of our mean-?eld approximation, we do not know with any certainty what these terms should be.Our assumption that they are proportional to the rate of irreversible work is by no means unique.(In-deed,we have tried other possibilities in related investi-gations and have arrived at qualitatively similar conclu-sions.)Without knowing more about the nature of the shear transformation zones,it will be di?cult to derive such interaction terms from?rst principles.
A better understanding of these interaction terms is especially important because these are the terms that will have to be modi?ed when we go beyond the mean-?eld theory to account for correlations between regions undergoing plastic deformations.We know from our sim-ulations that the active zones cluster even at stresses far below the plastic yield stress;and we know that plastic yield in real amorphous materials is dominated by shear banding.Thus,generalizing the present mean-?eld the-ory to one which takes into account spatial variations in the densities of shear transformation zones must be a high priority in this research program.
Finally,we return brie?y to the questions which moti-vated this investigation:How might the dynamical e?ects described here,which must occur in the vicinity of a crack tip,control crack stability and brittle/ductile behavior? As we have seen,our theoretical picture of viscoplasticity does allow large stresses to be transmitted,at least for short times,through plastically deforming materials.It should be interesting to see what happens if we incorpo-rate this picture into theories of dynamic fracture.
ACKNOWLEDGEMENTS
This research was supported by DOE Grant No.DE-FG03-84ER45108,by the DOE Computational Sciences Graduate Fellowship Program and,in part,by the MR-SEC Program of the National Science Foundation under Award No.DMR96-32716.
We wish particularly to thank Alexander Lobkovsky for his attention to this project and for numerous useful suggestions.We also thank A.Argon and https://www.doczj.com/doc/483454190.html,nge for guidance in the early stages of this work,J.Cahn for di-recting us to the papers of E.Hart,and https://www.doczj.com/doc/483454190.html,nger and A.Liu for showing us their closely related results on the dynamics of sheared foams.
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项目管理方法和项目实施方法的关系 在一个项目的执行过程中还同时需要两种方法：项目管理方法 和项目实施方法。 项目实施方法指的是在项目实施中为完成确定的目标如某个应 用软件的开发而采用的技术方法。项目实施方法所能适用的项目范围会更窄些，通常只能适用于某一类具有共同属性的项目。而在有的企业里，常常把项目管理方法和项目实施方法结合在一起，因为他们做的项目基本是属于同一种类型的。 实际上，只要愿意，做任何一件事情，我们都可以找到相应的 方法，项目实施也是一样。以IT行业的各种项目为例，常见的IT项目按照其属性可以分成系统集成、应用软件开发和应用软件客户化等，当然，也可以把系统集成和应用软件开发再分解成一些具备不同特性的项目。系统集成和应用软件开发的方法很显然是不一样的，比如说：系统集成的生命周期可能会分解为了解需求、确定系统组成、签订合同、购买设备、准备环境、安装设备、调试设备、验收等阶段;而应 用软件的开发可能会因为采用的方法不同而分解成不同的阶段，比如说采用传统开发方法、原型法和增量法就有所区别，传统的应用软件开发的生命周期可能分解成：了解需求、分析需求、设计、编码、测试、发布等阶段。 至于项目管理，可以分成三个阶段：起始阶段，执行阶段和结 束阶段。其中，起始阶段是为整个项目准备资源和制定各种计划，执
行阶段是监督和指导项目的实施、完善各种计划并最终完成项目的目标，而结束阶段是对项目进行总结及各种善后工作。 那么，项目管理方法和项目实施方法的关系是什么呢?简单的说，项目管理方法是为项目实施方法得到有效执行提供保障的。如果站在生命周期的角度看，项目实施的生命周期则是在项目管理的起始阶段和执行阶段，至于项目实施生命周期中的阶段分布是如何对应项目管理的这两个阶段，则视不同项目实施方法而不同。 一、实际意义 项目管理方法和项目实施方法对项目的成功都是有重要意义的，两者是相辅相成的，就如管理人员和业务技术人员对于企业经营的意义一样。从IT企业的角度看，任何一个IT企业如果要生产高质量的软件产品或者提供高质量的服务，都应该对自身的项目业务流程进行必要的分析和总结，并逐步归纳出自己的项目管理方法及项目实施方法，其中项目实施方法尤其重要，因为大部分企业都有自己的核心业务范围，其项目实施方法会比较单一，在这种情况下，项目管理方法可能会弱化，而项目实施方法会得到强化，两者会较紧密的结合在一起。只有总结出并贯彻实施符合企业自身业务的方法，项目的成功才不会严重依赖于某个人。在某种程度上，项目管理方法和项目实施方法也是企业文化的一部分。 从客户的角度看，如果希望得到有保障的产品或服务，那就既 需要关注提供产品或服务的企业是否有恰当的项目管理方法和项目 实施方法，也必须尊重该企业的项目管理措施与方法。
数字化校园建设与管理办法 第一章总则 第一条为加强学校数字化校园的建设和管理，规范数字化校园建设各项工作，提高学校信息化应用水平，保证信息化建设的实效性与可持续发展，实现学校信息资源和软硬件资源的有机集成和共享，充分发挥信息化建设成果在人才培养、科学研究、社会服务和文化传承创新等方面的支撑作用，根据相关的法律法规、国家和教育部对教育信息化建设的指导意见，以及《教育信息化十年发展规划2011—2020》、《陕西省教育信息化十年(2011—2020年)发展规划》、《陕西省教育信息化建设三年行动计划》等有关精神，特制定本办法。 第二条学校数字化校园建设，在学校信息化建设领导小组的领导下，由教务处信息中心统一规划、统一审批、统一建设、统一管理，并按照整体规划、分步实施的原则，以应用为中心，以数字资源建设为重点，逐步达到为师生、领导和管理部门提供良好的服务和辅助决策的建设目标，提升学校的综合竞争力。 第三条本办法适用于全校范围内各部门所拥有或负责管理运行的与数字化校园相关的基础网络、信息化公共平台、数字教育资源、管理信息系统、网站、数字监控网络及其相关网络接入设备、服务器、大容量存储设备等的建设和管理。 第二章管理机构与工作职责 第四条信息化建设领导小组是全面推进学校数字化校园建设的
最高管理与决策机构，负责审议学校数字化校园建设发展的中长期规划与经费预算；负责审议学校数字化校园建设、运维管理及校园网安全规章制度；明确学校数字化校园建设中各部门的责任分工、资源分配以及考核机制；对学校数字化校园建设中的重大问题和政策性问题进行决策。 第五条学校信息化建设领导小组负责对学校教育信息化建设发展的中长期规划进行论证，对数字化校园提出意见和建议；对学校数字化校园建设发展战略、政策、规划和发展中的重大问题提出建议和咨询意见；对学校数字化校园建设进程中各子项目的建设与验收提供技术层面与应用层面的意见或建议；指导学校数字化校园建设和信息化教育新模式的探索和研究工作。 第六条信息中心是学校数字化校园建设与管理具体实施的主体部门，全面负责学校数字化校园建设和管理工作。负责制定学校数字化校园建设发展的中长期规划与经费预算，制定学校数字化校园建设、运行与管理及保障校园网安全的规章制度；负责组织、实施学校数字化校园各项建设工作；负责对学校数字化校园建设相关项目和各部门申报的信息化新建和改造项目进行审核和实施；负责学校信息编码规范和数据标准的制定；负责学校信息资源共享、信息资源整合和系统集成；为各部门信息化建设提供技术指导、支持、监督和评比；负责公共平台应用的推广与培训；负责健全和完善信息化工作管理体系。 第七条各部门信息管理员负责本部门信息化相关数据的收集、整理和上报，负责本部门网站信息的更新、备份和维护；网络协管员
操作系统】Windows XP sp3 VOL 微软官方原版XP镜像◆ 相关介绍： 这是微软官方发布的，正版Windows XP sp3系统。 VOL是Volume Licensing for Organizations 的简称，中文即“团体批量许可证”。根据这个许可，当企业或者政府需要大量购买微软操作系统时可以获得优惠。这种产品的光盘卷标带有"VOL"字样，就取 "Volume"前3个字母，以表明是批量。这种版本根据购买数量等又细分为“开放式许可证”(Open License)、“选择式许可证(Select License)”、“企业协议(Enterprise Agreement)”、“学术教育许可证(Academic Volume Licensing)”等5种版本。根据VOL计划规定， VOL产品是不需要激活的。 ◆ 特点： 1. 无须任何破解即可自行激活，100% 通过微软正版验证。 2. 微软官方原版XP镜像，系统更稳定可靠。 ◆ 与Ghost XP的不同： 1. Ghost XP是利用Ghost程序，系统还原安装的XP操作系统。 2. 该正版系统，安装难度比较大。建议对系统安装比较了解的人使用。 3. 因为是官方原版，因此系统无优化、精简和任何第三方软件。 4. 因为是官方原版，因此系统不附带主板芯片主、显卡、声卡等任何硬件驱动程序，需要用户自行安装。 5. 因为是官方原版，因此系统不附带微软后续发布的任何XP系统补丁文件，需要用户自行安装。 6. 安装过程需要有人看守，进行实时操作，无法像Ghost XP一样实现一键安装。 7. 原版系统的“我的文档”是在C盘根目录下。安装前请注意数据备份。 8. 系统安装结束后，相比于Ghost XP系统，开机时间可能稍慢。 9. 安装大约需要20分钟左右的时间。 10. 如果你喜欢Ghost XP系统的安装方式，那么不建议您安装该系统。 11. 请刻盘安装，该镜像用虚拟光驱安装可能出现失败。 12. 安装前，请先记录下安装密钥，以便安装过程中要求输入时措手不及，造成安装中断。 ◆ 系统信息：
天津市东丽区职业教育中心学校“数字校园实验校”建设实施方案 一、信息化发展战略定位和愿景 根据学校十三五战略发展规划，在国家级示范校的基础上，立足东丽，面向天津，辐射全国，走向世界，实现“工学结合高要求、专业建设高品位、教育教 学高质量、就业服务高水平、学校发展高效益”的五高目标，“十三五”末期实现学校向世界一流水平的跨越，充分发挥示范和辐射作用。通过本期数字化校园项目建设，将我校打造成全国一流的中职数字化校园，构建技术先进、扩展性强、安全可靠、高速畅通、覆盖全校的校园网络环境。 建立一整套校园信息管理系统，为实现“环境数字化、管理数字化、教学数 字化、产学研数字化、学习数字化、生活数字化”提供全面的系统支持，使之成 为一个全面、集成、开放、安全的信息系统，成为一个网络化、数字化、智能化、虚拟化的新型教育、学习、实训和管理平台。通过数字化校园项目建设，推动教学模式变革，提高人才培养质量，促进学校对外交流。通过项目建设，使全体师 生提高信息化思维能力，养成信息化行为方式，遵守信息化交往规则，发展信息化职业能力。 二、数字化校园建设目标 按照“顶层设计、统一标准、数据共享、应用集成、硬件集群（虚拟化）” 的规划建设理念，实现： 1.为教学、科研、管理、生活提供一个开放、协同、高效、便捷的数字化 环境，实现规范高效的管理 2.为领导的决策提供实时有效的信息依据 3.为提升学校的核心竞争力，实现学校的跨越式发展提供有力的支撑 具体目标就是实现“六个数字化”： 环境数字化：构建结构合理、使用方便、高速稳定、安全保密的基础网络。 在此基础上，建立高标准的共享数据中心和统一身份认证及授权中心，统一门户平台以及集成应用软件平台，为实现更科学合理的数字化环境打下坚实的基础。 管理数字化：构建覆盖全校工作流程的、协同的管理信息体系，通过管理信息的同步与共享，畅通学校的信息流，实现管理的科学化、自动化、精细化，突出以人为本的理念，提高管理效率，降低管理成本。 教学数字化：构建综合教学管理的数字化环境，科学统一的配置教学资源， 提高教师、教室、实训室等教学资源的利用率，改革教学模式、手段与方法，丰 富教学资源，提高教学效率与质量。 产学研数字化：构建数字化产学研信息平台，为产学研工作者提供快捷、全面、权威的信息资源，实现教学、科研和实训一体化，提供开放、协同、高效的
Windows7 SP1官方原版 以下所有版本都为Windows7 SP1官方原版，请大家放心下载！ 32位与64位操作系统的选择：https://www.doczj.com/doc/483454190.html,/Win7News/6394.html 最简单的硬盘安装方法：https://www.doczj.com/doc/483454190.html,/thread-25503-1-1.html 推荐大家下载旗舰版，下载后将sources/ei.cfg删除即可安装所有版本，比如旗舰，专业，家庭版。 ============================================ Windows 7 SP1旗舰版中文版32位： 文件cn_windows_7_ultimate_with_sp1_x86_dvd_u_677486.iso SHA1:B92119F5B732ECE1C0850EDA30134536E18CCCE7 ISO/CRC:76101970 cn_windows_7_ultimate_with_sp1_x86_dvd_u_677486.iso.torrent(99.63 KB, 下载次数: 326189) Windows 7 SP1旗舰版中文版64位： 文件cn_windows_7_ultimate_with_sp1_x64_dvd_u_677408.iso SHA1: 2CE0B2DB34D76ED3F697CE148CB7594432405E23 ISO/CRC: 69F54CA4 cn_windows_7_ultimate_with_sp1_x64_dvd_u_677408.iso.torrent(128.17 KB, 下载次数: 197053)
项目管理思路（提纲） 原则：规范创新项目管理方法，提供标准化的项目管理体系。（这次的思路主要考虑整体、不突出重点。） 一、工程项目管理的基本内容： 1、项目部管理 2、前期管理 3、招标合同管理 4、设计管理 5、总承包管理 6、进度管理 7、质量管理 8、成本管理 9、竣工（收尾）管理 二、项目部管理 1、项目部组织结构：项目部的构成根据项目的发展进度再不断进行调整，先补充预算员、资料员及熟悉酒店项目的机电工程师； 2、项目部职责（分工）：落实责任到岗位，落实责任到人，着重把后面的所有管理内容一项不漏的分配到具体的管理人员上，真正做到“权责明晰，有据可依”； 3、加强项目管理人员的培训及学习工作，紧跟社会行业的前进步伐，提高项目管理人员的业务能力，为新项目的顺利进行提供坚实的基
础； 4、项目部管理制度：以公司现有的规章制度及考核制度为基础，再根据新情况进行一些适当补充与调整。 三、前期管理 1、各种手续、审批报建工作的推进及跟踪，无法办理的事项及时将具体情况及原因反馈给公司领导； 2、联络街道办和公证处对本项目周边毗邻建筑物的现状（特别是裂缝、下沉）进行拍照确认并公证； 3、拆除施工场地内的原有基础或其他障碍物；通水(自来水公司)、通电、办理临时占道、开路口(城管局) 及其他相关手续； 4、根据公司领导的要求及项目实际情况编制项目总开发计划； 四、招标合同管理 1、除审查入围单位的资质等级、营业执照、财务状况外，还应着重对入围单位的办公地点、在建项目（生产厂房）针对人员、质量、安全、环境等进行实地考察，以确定是否满足我方质量、进度等综合要求； 2、根据总开发计划编制专业分包与主要材料、设备的进场计划，明确进场时间；根据专业分包与主要材料、设备的进场计划编制招标、采购计划，并严格执行； 3、对于专业分包，要细化、深化各类发包工程内容的自身招标条件，应事先研究各工程内容建设的时间、验收、保修、交接、资料、协作、费用、安全、场地等接口配合条件，就甲方发包(含总承包)的各内容
项目一：数字化校园特色项目建设计划 一、需求论证 信息技术的飞速发展，迅速地改变着人们的学习、工作和生活，也改变着人们的思想、观念和思维方式。这一切都对快速发展中的职业教育和职业学校提出了十分严峻的挑战。现代信息技术正在向职业学校教学、科研、管理的每一个环节渗透，将改变传统的教学模式并大幅度提高教育资源的利用效率。数字化校园、网上学校已被人们熟悉，职业教育正在走向全面的信息化。 数字化校园的建设应用是教育系统信息化的关键，在职业学校建设数字化校园，对于促进教师和学生尽快提高应用信息技术的水平,促进学校教学改革，推行素质教育，促进教学手段的现代化水平,为教师提供一种先进的辅助教学工具、提供丰富的资源库，全面提高学校现代化管理水平，加强学校与外界交流等方面都具有重要作用。 2005年学校完成校园网建设，同时接入因特网，校园网覆盖了所有使用计算机的实验室、各处办公室、各专业组。目前校园网已覆盖整个校园。但数字化教与学以及服务区域职业教育、实现教育资源共享的能力还远远不够。作为一所综合性国家级重点职业学校，以及建设国家中等职业教育改革发展示校的要求，要使其发挥辐射带动作用，达到资源利用最大化，迫切需要我校建设数字化校园，将更大的注意力放在信息化的深入应用上，及早做好规划，将信息化发展推向新水平。 二、建设目标
数字化校园建设的目标主要包括：一是完善校园网基础设施建设，构建技术先进、扩展性强、安全可靠、高速畅通、覆盖本部、一分部、实训基地的校园网络环境；二是建设全校防盗系统；三是完善校园广播系统；四是各种资源应用平台建设；五是建设校园一卡通。 学校通过构建技术先进、扩展性强、安全可靠、高速畅通、覆盖全校的校园网络环境，建立全校公共信息系统，为教与学提供先进数字化管理手段，提高管理效率；建立功能齐全的教学管理系统；配合“工学结合”教学模式，建设容丰富的网络教学资源平台，实现数据资源共享，提高全校师生的信息化水平素养。通过数字化校园的建设项目，为培养高技能应用型人才和服务社会搭建公共服务平台。 三、建设思路 以服务专业建设为出发点，建设数字化校园和教学资源中心。构筑信息交流与资源共享平台，创建开放的教学资源环境，实现优质教学资源网上共享，为实用型技能人才的培养和构建现代化学习环境搭建公共平台，提高管理效率与教学水平。提高全校师生信息化水平素养，以网络为基础，利用先进的信息手段和工具，将学校的各个方面，实现环境（包括网络、设备、教室等）、资源（如图书、讲义、课件等）、活动（包括教、学、管理、服务、办公等）的数字化，逐步形成一个数字校园空间，从而使现实校园在时间和空间上获得延伸，完成数字校园建设，对本地区职业教育信息化建设和发展起到示与带动作用。 四、建设容 （一）校园安全防盗系统
Microsoft 微软官方原版（正版）系统大全 微软原版Windows 98 Second Edition 简体中文版 https://www.doczj.com/doc/483454190.html,/viewthread.php?tid=16446&page=1&extra=#pid125031 微软原版Windows Me 简体中文版 https://www.doczj.com/doc/483454190.html,/viewthread.php?tid=16448&highlight=%CE%A2%C8%ED%D4%AD %B0%E6 微软原版Windows 2000 Professional 简体中文版 https://www.doczj.com/doc/483454190.html,/viewthread.php?tid=16447&highlight=%CE%A2%C8%ED%D4%AD %B0%E6 微软原版Windows XP Professional SP3 简体中文版 https://www.doczj.com/doc/483454190.html,/viewthread.php?tid=16449&page=1&extra=#pid125073微软原版Windows XP Media Center Edition 2005 简体中文版 https://www.doczj.com/doc/483454190.html,/viewthread.php?tid=16451&highlight=%CE%A2%C8%ED%D4%AD %B0%E6 微软原版Windows XP Tablet PC Edition 2005 简体中文版 https://www.doczj.com/doc/483454190.html,/viewthread.php?tid=16450&highlight=%CE%A2%C8%ED%D4%AD %B0%E6 微软原版Windows Server 2003 R2 Enterprise Edition SP2 简体中文版(32位) https://www.doczj.com/doc/483454190.html,/viewthread.php?tid=16452&highlight=%CE%A2%C8%ED%D4%AD %B0%E6 微软原版Windows Server 2003 R2 Enterprise Edition SP2 简体中文版(64位) https://www.doczj.com/doc/483454190.html,/viewthread.php?tid=16453&highlight=%CE%A2%C8%ED%D4%AD %B0%E6 微软原版Windows Vista 简体中文版(32位) https://www.doczj.com/doc/483454190.html,/viewthread.php?tid=16454&highlight=%CE%A2%C8%ED%D4%AD %B0%E6 微软原版Windows Vista 简体中文版(64位) https://www.doczj.com/doc/483454190.html,/viewthread.php?tid=16455&highlight=%CE%A2%C8%ED%D4%AD %B0%E6 微软原版 Windows7 SP1 各版本下载地址： https://www.doczj.com/doc/483454190.html,/viewthread.php?tid=12387&highlight=%CE%A2%C8%ED%D4%AD %B0%E6 微软原版 Windows Server 2008 Datacenter Enterprise and Standard 简体中文版(32位) https://www.doczj.com/doc/483454190.html,/viewthread.php?tid=16457&highlight=%CE%A2%C8%ED%D4%AD %B0%E6 微软原版 Windows Server 2008 Datacenter Enterprise and Standard 简体中文版(64位) https://www.doczj.com/doc/483454190.html,/viewthread.php?tid=16458&highlight=%CE%A2%C8%ED%D4%AD %B0%E6 微软原版 Windows Server 2008 R2 S E D and Web 简体中文版(64位) https://www.doczj.com/doc/483454190.html,/viewthread.php?tid=16459&highlight=%CE%A2%C8%ED%D4%AD %B0%E6
中国建设银行科技应用规划项目项目管理章程和工作方法 中国建设银行 2020年4月2日
目录 1项目人员角色和职责3 2项目运行中的沟通机制 (5) 3项目文档资料管理机制8 4项目人员的考核机制 (12) 5项目培训机制 (14) 6项目验收机制15 项目人员角色和职责 项目领 导委员会 项目总监 /项目管理办公 项目小组 项目领 导委员会 项目总监 质量总监 项目经理 项目小组 1) 项目领导委员会：
由双方的高层领导参加，直接负责项目的成功实施，负责： a)确定项目目标和方向 b)保证资源合理调动，支持项目的推行 c)促使管理层对项目的全力参与和支持 d)验收和审批项目成果 e)授权项目经理开展工作 2)项目总监和质量总监： 项目总监由双方选出的高层领导担任，主要负责： a)对项目过程进行指导和监督 b)确认双方工作职责和安排 c)组织协调项目所需资源的合理调配 d)按项目进度向项目领导委员会汇报 e)定期对项目的工作进度进行监督 f)对项目成果进行确认和验收 毕博管理咨询将另派高层管理人员作为本项目的质量总监，主要负责： a)对本项目的整体质量进行检查和考核 3)项目经理： 项目经理成员由双方的项目经理组成，具体负责： a)策划项目推进和控制项目进程 b)确认项目小组及其成员的工作职责 c)指导及安排项目小组的日常工作 d)定期安排双方沟通、及时调整工作安排 e)现场处理双方可能产生的意见不一致 f)执行项目所需资源的有效调配 g)组织对项目成果的确认和验收 4)项目小组：
项目小组将由小组负责人、咨询顾问、行业专家以及中国建设银行的项目参与人员共同组成。项目小组的职责包括： a)确定项目的工作步骤和具体工作方法 b)具体开展项目工作，包括：收集数据和信息，分析并确定问题，设计解决方案， 讨论和修改工作成果，协助实施 c)根据项目要求，在规定的时间内提交符合质量要求的项目设计方案 项目运行中的沟通机制
中小学数字化校园管理系统软件 拟 定 方 案
目录 一、数字校园基础平台： (3) 二、协同办公系统： (5) 三、招生管理系统： (6) 四、学籍管理系统： (7) 五、学费管理系统： (7) 六、学生管理系统： (8) 七、学生请销假管理： (8) 八、量化考核管理系统： (8) 九、教务管理系统： (9) 十、成绩管理系统： (9) 十一、离校管理系统： (10) 十二、资产管理系统： (10) 十三、人事档案管理系统： (11) 十四、数字化图书馆教学资源库、精品课程及网上教学平台： (11)
“数字化校园管理系统” “数字校园管理系统”是针对职业院校信息化建设，研发的数字化校园管理系统。通过电脑或手机等终端，为校长、老师、学生、行政办公人员、学生父母、来访用户及相关应用人员提供高效、便捷的一站式信息服务。实现了校园内各类应用软件高效集成和数据资源高度共享，是最适合中学高中及大学校园信息化建设的管理软件。 下面是平台界面示意图： 一、数字校园基础平台：
数字校园管理系统特点： 产品开发以学校为原型， 技术选型性价比更高。 采用windows server +php + mysql + apache的技术架构。 优势：采用win server 作为操作系统，更容易维护，也符合学校服务器现有情况 采用mysql开源数据库，无需支付软件授权费用，因为mysql是一个开源免费的数据库。但是其性能及稳定性堪称一流，许多大型网站系统都在使用。 PHP是全世界使用量排名第四的编程语言，在B/S结构的系统中有其得天独厚的优势。 我方在提供以开发完毕的整套系统的基础上，后期可根据学校需求进行系统的第二次开发，以适应学校的需求。 数字校园管理系统：多终端访问： 数字校园管理系统基础平台包含内容：
精心整理正版Windows系统下载+正版密钥 2010-05-3011:49 喜欢正版Windows系统 这是我收集N天后的成果，正版的Windows系统真的很好用，支持正版！大家可以用激活工 具激活！现将本收集的下载地址发布出来，希望大家多多支持！ Windows98第二版（简体中文） 安装序列号：Q99JQ-HVJYX-PGYCY-68GM3-WXT68 安装序列号：Q4G74-6RX2W-MWJVB-HPXHX-HBBXJ 安装序列号：QY7TT-VJ7VG-7QPHY-QXHD3-B838Q WindowsMillenniumEdition(WindowME)（简体中文） 安装序列号：HJPFQ-KXW9C-D7BRJ-JCGB7-Q2DRJ 安装序列号：B6BYC-6T7C3-4PXRW-2XKWB-GYV33 安装序列号：K9KDJ-3XPXY-92WFW-9Q26K-MVRK8 Windows2000PROSP4（简体中文） SerialNumber:XPwithsp3VOL微软原版（简体中文） 文件名:zh-hans_windows_xp_professional_with_service_pack_3_x86_cd_vl_x14-74070.iso 大小:字节 MD5:D142469D0C3953D8E4A6A490A58052EF52837F0F CRC32:FFFFFFFF 邮寄日期(UTC)：5/2/200812:05:18XPprowithsp3VOL微软原版（简体中文）正版密钥： MRX3F-47B9T-2487J-KWKMF-RPWBY(工行版)（强推此号！！！） QC986-27D34-6M3TY-JJXP9-TBGMD(台湾交大学生版) QHYXK-JCJRX-XXY8Y-2KX2X-CCXGD(广州政府版)
微软MSDN官方（简体）中文操作系统全下载 这不知是哪位大侠收集的，太全了，从DOS到Windows，从小型系统到大型系统，从桌面系统到专用服务器系统，从最初的Windows3.1到目前的Windows8，以及Windows2008，从16位到32位，再到64位系统，应有尽有。全部提供微软官方的校验文件，这些文件都可以在微软官方MSDN订阅中得到验证，完全正确！ 下载链接电驴下载，可以使用用迅雷下载，建议还是使用电驴下载。你可以根据需要在下载链接那里找到你需要的文件进行下载！太强大了！！！ 产品名称: Windows 3.1 (16-bit) 名称: Windows 3.1 (Simplified Chinese) 文件名: SC_Windows31.exe 文件大小: 8,472,384 SHA1: 65BC761CEFFD6280DA3F7677D6F3DDA2BAEC1E19 邮寄日期(UTC): 2001-03-06 19:19:00 ed2k://|file|SC_Windows31.exe|8472384|84037137FFF3932707F286EC852F2ABC|/ 产品名称: Windows 3.2 (16-bit) 名称: Windows 3.2.12 (Simplified Chinese) 文件名: SC_Windows32_12.exe 文件大小: 12,832,984 SHA1: 1D91AC9EB3CBC1F9C409CF891415BB71E8F594F7 邮寄日期(UTC): 2001-03-06 19:21:00 ed2k://|file|SC_Windows32_12.exe|12832984|A76EB68E35CD62F8B40ECD3E6F5E213F|/ 产品名称: Windows 3.2 (16-bit) 名称: Windows 3.2.144 (Simplified Chinese) 文件名: SC_Windows32_144.exe 文件大小: 12,835,440 SHA1: 363C2A9B8CAA2CC6798DAA80CC9217EF237FDD10 邮寄日期(UTC): 2001-03-06 19:21:00 ed2k://|file|SC_Windows32_144.exe|12835440|782F5AF8A1405D518C181F057FCC4287|/ 产品名称: Windows 98 名称: Windows 98 Second Edition (Simplified Chinese) 文件名: SC_WIN98SE.exe 文件大小: 278,540,368 SHA1: 9014AC7B67FC7697DEA597846F980DB9B3C43CD4 邮寄日期(UTC): 1999-11-04 00:45:00 ed2k://|file|SC_WIN98SE.exe|278540368|939909E688963174901F822123E55F7E|/ 产品名称: Windows Me 名称: Windows? Millennium Edition (Simplified Chinese) 文件名: SC_WINME.exe
项目管理方法 项目管理方法是关于如何进行项目管理的方法，是可在大部分项目中应用的方法。主要有：阶段化管理、量化管理和优化管理三个方面. 管理概述 项目管理是一个管理学分支的学科，指在项目活动中运用专门的知识、技能、工具和方法，使项目能够在有限资源限定条件下，实现或超过设定的需求和期望。项目管理是对一些与成功地达成一系列目标相关的活动(譬如任务)的整体。这包括策划、进度计划和维护组成项目的活动的进展。项目管理方法是关于如何进行项目管理的方法，是可在大部分项目中应用的方法。在项目管理方法论上主要有：阶段化管理、量化管理和优化管理三个方面。[1] 阶段管理 阶段化管理指的是从立项之初直到系统运行维护的全过程。根据工程项目的特点，我们可将项目管理分为若干个小的阶段。 市场信息 1）市场信息方面可分为：信息采集、信息分析、工程项目立项及项目申请书的编写。 ①信息采集：可分为工程项目信息与常规设备与器材的市场信息的采集。这些信息通过业务员或其它通道获得，一旦获得后，信息提供者应以书面形式向公司有关部门予以报告。 ②信息分析：公司在这方面应该设立专门的部门对各种信息进行分类、编辑、管理、核实、分析与论证，在考虑项目时不但要看社会是否需要，而且还要研究个人、组织或社会是否有能力投入足够的资源将其实现，实现之后能否为资源投入者和社会真正带来利益。通过对项目的可行性研究为信息的确定提供切实可行的依据。并监督业务工作人员的
工作效率以及其绩效评价。 ③工程项目立项：根据信息分析部门所提供的分析与认证报告，确定信息的处理方式，并上报公司决策层予以决策。公司决策层通过信息分析部门的信息分析报告结合公司的经营状况，对信息进行确定是否立项，一旦立项，就要分析会有哪些承约商参加投标，各自的优势以及他们同客户的关系。主要考虑的因素包括自身的技术能力、项目风险、资源配置能力及其它因素。同时也可对信息分析部门的工作效率以及其绩效评价。 申请书填写 项目申请书：当决定参加投标竞争的时候上，就需要完成一份项目的申请书或称为投标书，一份完整的申请书一般包括三个部分的内容，即技术、管理、成本三个方面。如果是一份较复杂的申请书，这三部分可能是三个独立的册子： 技术部分的目的是让客户认识到：承约商对其需求和问题的理解，并且能够提供风险最低且收益最大的解决方案。 管理部分的目的是使客户确信，承约商能够做好项目所提出的工作，并且收到预期的结果。 成本部分的目的是使客户确信，承约商申请项目所提出的价格是现实的、合理的。 这一部分任务将由公司的技术支持部门根据市场信息部门的有关报告完成，同样也可以通过其工作效率及质量对其进行绩效评价。 申请书完成后 在项目申请书完成的同时，市场信息部门的所有部门都应密切注视该项目的进展情况，及时更新项目的最新状况，并通报各有关部门特别是技术支持部门，使该部门能根据项目的最新情况调整项目申请书。以增大我们在项目中的竞争能力。 在合同的签订即项目确定之后，项目管理又可划分为项目准备阶段、项目实施阶段、竣工验收阶段及系统运行维护阶段等。各阶段的工作内容的不同，其实施与管理也应各异。 ①项目准备阶段：其项目实施管理方式的确定(即项目组织)，各种资源的配备与落实，以及具体项目实施方案的进一步确定。即根据项目的特点，对项目作业进行分解，确定其阶段性成果验收，以及必要的监督反馈，这样就能够很好地解决项目组织与客户的分歧，增加项目风险的可控性。 ②项目实施阶段：根据项目实施的具体方案，并以各阶段性成果按其技术要求、质量保证进行验收。这样，在每个阶段完成后，客户和项目
附件2 内蒙古建筑职业技术学院院长科研基金课题申请·评审书 课题名称：高职院校校园数字化建设系统研究 主持人： 所在部门：） 联系电话： 申请日期：
填报说明 一、课题（项目）主持人必须从事教学或管理工作五年以上并具有中级以上职称。课题主持人必须是该课题的实际主持者和指导者，并在课题研究中担负实质性的任务。 二、课题（项目）主持人原则上不超过55岁。鼓励35岁以下优秀青年教师和科技人员特别是博士、硕士学位的年轻教师申报。申报项目的课题组必须具有良好的政治思想素质、独立开展和组织教育教学研究工作的能力，有较充分的前期准备和相应合理的学术梯队。 三、课题论证应尽量充分。研究计划和阶段成果应尽量明确。 四、申请书各项内容，要实事求是，逐条认真填写。表达要明确、严谨，字迹要清晰易辩。外来语要同时用原文和中文表达。第一次出现的缩写词，须写出全称。 五、申请书复印时用A4复印纸，于左侧装订成册。各栏空格不够时，请自行加页。一式三份，由所在部门签署意见后，报高职教育研究所。 六、每一个课题的主要成员(含主持人)只允许申报一个项目。 七、本申请书与任务批准书同时作为立项依据。
课题主持人承诺 我确认本申请书及附件内容真实、准确。如果获得资助，我将认真履行课题负责人职责，积极组织开展研究工作，合理安排研究经费，按时报送有关材料并接受检查。若申请书及附件内容失实或在课题执行过程中违反科研项目管理的有关规定，本人将承担全部责任。 负责人签字： 20 年月日 课题依托部门承诺 本部门已按照课题申报要求对课题主持人的资格及课题申请书内容进行了审核，课题主持人及课题组主要成员具备课题研究的素质与水平，能够保证课题研究计划实施所需的人才、物力及工作时间，课题如获资助，本部门将根据学院要求和课题申请书内容，落实课题研究所需其他条件，并按照学院科研课题管理有关规定，认真履行课题依托部门的管理职责。 部门公章负责人签章 20 年月日
Windows7官方个版本正版镜像下载地址 简体中文旗舰版： 32位：下载地址：ed2k://|file|cn_windows_7_ultimate_x86_dvd_x15-65907.iso|2604238848|D6F139D7A45E81B 76199DDCCDDC4B509|/ SHA1：B589336602E3B7E134E222ED47FC94938B04354F 64位：下载地址：ed2k://|file|cn_windows_7_ultimate_x64_dvd_x15-66043.iso|3341268992|7DD7FA757CE6D2D B78B6901F81A6907A|/ SHA1：4A98A2F1ED794425674D04A37B70B9763522B0D4 简体中文专业版： 32位：下载地址：ed2k://|file|cn_windows_7_professional_x86_dvd_x15-65790.iso|2604238848|e812fbe758f 05b485c5a858c22060785|h=S5RNBL5JL5NRC3YMLDWIO75YY3UP4ET5|/ SHA1：EBD595C3099CCF57C6FF53810F73339835CFBB9D 64位：下载地址：ed2k://|file|cn_windows_7_professional_x64_dvd_x15-65791.iso|3341268992|3474800521d 169fbf3f5e527cd835156|h=TIYH37L3PBVMNCLT2EX5CSSEGXY6M47W|/ SHA1：5669A51195CD79D73CD18161D51E7E8D43DF53D1 简体中文家庭高级版： 32位：下载地址：ed2k://|file|cn_windows_7_home_premium_x86_dvd_x15-65717.iso|2604238848|98e1eb474f9 2343b06737f227665df1c|h=GZ7FZE7XURI5HNO2L7H45AGWNOLRLRUR|/ SHA1：CBA410DB30FA1561F874E1CC155E575F4A836B37 64位：下载地址：ed2k://|file|cn_windows_7_home_premium_x64_dvd_x15-65718.iso|3341268992|9f976045631 a6a2162abe32fc77c8acc|h=QQZ3UEERJOWWUEXOFTTLWD4JNL4YDLC6|/ SHA1：5566AB6F40B0689702F02DE15804BEB32832D6A6 简体中文企业版： 32位：下载地址：ed2k://|file|cn_windows_7_enterprise_x86_dvd_x15-70737.iso|2465783808|41ABFA74E5735 3B2F35BC33E56BD5202|/ SHA1：50F2900D293C8DF63A9D23125AFEEA7662FF9E54 64位：下载地址：ed2k://|file|cn_windows_7_enterprise_x64_dvd_x15-70741.iso|3203516416|876DCF115C2EE 28D74B178BE1A84AB3B|/ SHA1：EE20DAF2CDEDD71C374E241340DEB651728A69C4
项目管理工作心得感想 项目管理工作在企业是很重要的。项目管理作为企业及组织的一种管理方法,已经在实际的经济运作中扮演了越来越重要的角色并起到了越来越高效的成果。下面是为大家整理的项目管理工作心得感想，供你参考! 项目管理工作心得感想篇1 两天认真听了《全面项目化管理》这门课，***教授从五大类分别给我们详细讲述了全面项目化管理基础思想、成功项目的必备条件、全面项目化、项目化管理和全面、项目化管理的导入。通过学习将我们如何运用全面项目化管理又提升到一个新的高度，让我们又发现了诸多平时工作中存在的问题，也对我们今后的工作起到了指导与改正的作用，真正是受益匪浅。 通过赵教授对专业理论知识的阐述再到典型案例的剖析，做得好的方面也得到了课程中理论知识的支持，对一些常见的错误也以鲜活的案例加以呈现，让我们将日常工作中常犯的错误集中展现并一一剖析其错误所在以及对工作的影响，对我们今后的工作起到了一定的改善作用。 老师讲项目的标准化时，重点说明了要重视基本习惯的培养，可以大大提高工作质量，任何规范的基础都很重要。还有项目经理的选择，应具备的三大素养和应具备的工作能力等，这一点我在工作中深有体会。 无论是企业还是个人，一个好的完善的计划必定能够帮助我们更快更有效的确定行动方向，从而能达到事半功倍的效果。无论办什么事情都应明确其目的和意义，有个打算和安排。有了计划，就有了明确的奋斗目标，具体的工作程序，就可以更好地统一大家的思想，协调行动，增强工作的自觉性，减少盲目性，调动员工的积极性和创造精神，合理地安排和使用人力、物力，少走弯路，少受挫折，保障工作顺利进行，避免失误。计划一旦形成，就在客观上变成了对工作的要求，对计划实施者的约束和督促，对工作进度和质量的考核标准。这样，计划又反过来成了指导和推动工作前进的动力。总之，搞好工作计划，是建立部门正常工作秩序，提高工作效率必不可少的程序和手段。编制好工作计划，对于我们的工作，都有十分重要的意义。为提高工作效率，我们还编制了相关工作计划进度表，部门每一个人在工作例会上必须对自己一周的工作完成情况进行汇报，然后由经理再对部门的工作做出总结，通过表格计划管理有效的加快了工作进度。 作为一个优秀的项目经理必须具备一定的管理能力、工作能力及执行能力，还需具备良好的心理素质和抵御压力的能力和具备良好的素养。我们要为公司广结良缘，广交朋友，形成公司与政府部门之间沟通的桥梁，形成人和的氛围和环境。为此要把握交往的技巧、艺术、原则。能力+人脉=成功。维持良好的人脉关系有效的实现工作成功的目标。就在今年
第二章 软硬件基本功能演示 在详细学习每个部分之前，我们先通过一个实例来全程演示Quartus Ⅱ以及便携式EDA-Ⅰ实验平台的基本功能及实验流程，帮助大家提升学习兴趣。 选择4位的3选1多路选择器为例，利用Quartus Ⅱ完成基于VHDL 语言输入的工程设计过程， 包括创建工程文件、VHDL 程序输入、编译综合、波形仿真验证、管脚分配以及下载等。 实例原理介绍：3选1多路选择器是通过控制电路实现三路四位数据的选择输出显示，sel 作为选择信号，d0,d1,d2 sel=“01”时选择选择d1，其他情况选择d2。 1、 创建工程文件 Quartus Ⅱ软件的工程文件是指所有的设计文件、软件源文件和完成其他操作所需的相关文件的总称。 双击Quartus Ⅱ软件图标，进入如下界面： 图2.1 Quartus Ⅱ软件界面 选择左上角的File —>New Project Wizard ，打开新建工程向导。
点击页面下方的next，进入新建工程向导。 图 2.2 新建工程向导第1页 在下图2.1.2的对话框，分别按照提示输入新建工程所在位置、工程名称（mux3_1）和顶层实体名称（mux3_1）。注意：默认工程名与顶层实体名一致。 图 2.3 新建工程向导第2页 完成后点击“Next”按钮，进入下一步，在图示2.4新建工程向导第3页中可以添加工程所需的源文件以及设置用户库。
图 2.4 新建工程向导第3页 这一步一般直接点击“Next”跳过，进入下一步，选择目标器件。在“Family”下拉列表中选择器件系列为Flex10K，在Target device选项中选中Specific device selected in ‘Available devices’list，依据实验平台的型号，确定器件型号Available device 为。 图 2.5 新建工程向导第4页