当前位置：文档库 › readdata

readdata

Journal of Analytical and Applied Pyrolysis

58–59(2001)453–463

Volatile products of

pyrolysis

celluloses

G.Dobele a,*,D.Meier b ,O.Faix b ,S.Radtke b ,

G.Rossinskaja a ,G.Telysheva a

Lat 6ian State Institute of Wood Chemistry ,27,Dzerbenes St .,LV -1006,Riga ,Lat 6ia

Federal Research Centre for Forestry and Forest Products ,

Institute for Wood Chemistry and Chemical Technology of Wood ,Leuschnerstr .91,D -21031,

Hamburg ,Germany Received 5May 2000;received in revised form 20June 2000;accepted 3August 2000

Abstract

Analytical pyrolysis combined with gas chromatography (Py-GC)has been used to study the composition of volatile products of different commercial celluloses impregnated with various amounts of phosphoric acid.The in?uence on the yields of levoglucosan and levoglucosenone was studied taking into account the supramolecular structure,degree of polymerization,hydrophilic properties and pretreatment conditions of the celluloses.It was found that levoglucosenone predominates in the volatiles of acid catalyzed pyrolysis.However,the relative total amount of both 1,6-anhydrosaccharides varied only in a narrow range of 75–85%regardless of the impregnation and pretreatment conditions of the celluloses.The maximum progress in cellulose dehydration reactions resulting in the highest levoglucosenone content of 78%is reached with Munktell microcrystalline cellulose owing to its low accessibility and high ordered supramolecular structure.For pulps with a less ordered cellulosic supramolecular structure,breaking of glycosidic bonds with the formation of levoglucosan besides levoglucosenone occurred and the relative amount of non-dehydrated anhydrosaccharides increased.?2001Elsevier Science B.V.All rights reserved.

Keywords :Cellulose;Fast pyrolysis;Levoglucosenone;Levoglucosan;Pretreatment,Catalysis

https://www.wendangku.net/doc/e315056452.html, /locate /jaap

*Corresponding author.

454G.Dobele et al./J.Anal.Appl.Pyrolysis58–59(2001)453–463

1.Introduction

It has been shown earlier[1,2]that fast pyrolysis of cellulosic raw materials impregnated with phosphoric acid can yield a bio-oil with a high content of 1,6-anhydrosaccharides,suitable as a high value added feedstock for organic synthesis.1,6-anhydrosaccharides have high functionality and conformation rigid-ity,and?nd application as chiral building blocks for preparation of biologically important and structurally diverse products identical with natural ones[3]. Impregnation of cellulose,being a primary stage for a whole range of chemical processes,including pyrolysis,is mainly aimed at changing the properties of the material.The properties of cellulose impregnated with phosphoric acid depend on both the pretreatment temperature and structure of the cellulosic raw material[4]. Amorphous cellulose is characterized by a higher capacity for esteri?cation[5].

It is known that the interaction of cellulose with phosphoric acid results in the change of the primary system of hydrogen bonds of the polymer and its esteri?ca-tion[6].Apart from this,even low pretreatment temperatures of the impregnated raw material may lead to a change in the degree of polymerization and crystallinity index of cellulose.The above-mentioned factors have a pronounced effect on the thermolysis of cellulosic materials,namely,on the ratio of the main reactions such as depolymerization and dehydration,and,correspondingly,on the composition of volatile products[2].

The aim of the present study was to investigate the variations in the composition of the two main volatile products levoglucosan and levoglucosenone,and their dependence on the crystallinity index,degree of polymerization of cellulose,condi-tions of impregnation with phosphoric acid incl.pretreatment temperature.

2.Experimental

2.1.Initial materials

Four cellulose samples were used:Munktell and Thermocell microcrystalline celluloses,Taircell cellulose from the sulphate pulping process and recycled Kraft-pulp.All celluloses used are commercially available excluding microcrystalline Thermocell cellulose.The latter is a sample from an experimental batch,which was produced by the method developed at the IWCh,Latvia[7].

Crystallinity index was calculated based on the data of X-ray diffractometry[8]. Degree of polymerization was determined by viscosity measuring in cellulose cadoxene solutions(relative error of the method5%)[9].

2.2.Impregnation with phosphoric acid

87%phosphoric acid(puriss.,Fluka)was used.An aqueous solution of phospho-ric acid(3.5,5and7wt.%based on dry cellulose)was mixed with cellulose (cellulose/acid solution=1:5).The water was evaporated under vacuum and the impregnated material was dried at40°C under reduced pressure.

455

G.Dobele et al./J.Anal.Appl.Pyrolysis58–59(2001)453–463

2.3.Pretreatment of impregnated cellulose

The dried cellulose samples were heated for1h at100and160°C.

2.4.Water sorption

The equilibrium sorption of water vapor was studied at295K using vacuum sorption balances(a sensitivity of quartz spirals of1.5–2.0mm mg?1).Before measuring,the pulp samples were conditioned within a sorption device for4h at 295K and a pressure of1Pa.The equilibrium time for each relative water vapor pressure,p/p0,was20–30h.The accuracy of sorption measuring was0.5%.The sorption isotherms were analyzed according to the comparative method along with the Brunauer–Emmet–Teller(BET)method.The sorption in the monolayer a m (mmol g?1)was calculated from BET equation in the linear form using the least squares method:

p/p0 a·(1-p/p0)=

a m·C

C-1

a m·C

·(p/p0)

where a is the sorption at the pressure p/p0;C is the energy constant.

2.5.Analytical pyrolysis-gas chromatography(Py-GC)

A CDS Pyroprobe100combined with a gas chromatograph(CP9000)was used to pyrolyze and analyze a70m g sample.Pyrolysis took place in helium(99.555% purity)atmosphere.The same gas was used as carrier gas for GC.Pyrolysis temperature was set to500°C.Heating rate was600°C s?1and pyrolysis time was 10s.A DB-1701column(60m×0.25mm,0.25m m?lm)was used for the separation of the monomeric volatiles.Further details of the procedure can be found elsewhere[10].

3.Results and discussion

The cellulose samples used in this study have different degrees of polymerization (DP)and supramolecular structures,which are re?ected by crystallinity index values characterizing the number of the ordered regions of a macromolecule(Table 1).The DP value of recycled Kraft pulp is too high due to contaminations.

It is known that the transformations of non-treated cellulose at temperatures below200°C do not cause any notable changes,neither in its supramolecular structure and DP nor in the functional and elementary compositions[11].However, as shown in Table1,the indices of crystallinity of celluloses impregnated with7% phosphoric acid and pretreated at160°C tend to decrease.The number of the ordered microregions of the macromolecule tends to decrease most signi?cantly in the case of regenerated Kraft pulp.The least changes are observed for Munktell cellulose.

456G.Dobele et al./J.Anal.Appl.Pyrolysis58–59(2001)453–463

Table1

Crystallinity index and degree of polymerization of celluloses

Cellulose

Degree of polymerization Crystallinity index(%)

Untreated Impregnated7%H3PO4,160°C,1h

85.7

Munktel85.7

200

Therrmocell30072.3

71.5

Taircell1040

78.5

76.7

Kraft-pulp

240072.658.6

The data on the variation in the crystallinity index of impregnated celluloses correlate,to a certain extent,with different accessibilities of blank celluloses studied here.The data on sorption–desorption of water vapors of the investigated cellu-loses(Table2)show that the amount of sorbed water decreases as the degree of cellulose ordering increases,from195.2to89.9mg g?1,respectively for Kraft and Munktell celluloses.

According to increasing crystallinity index values,the celluloses are arranged in the following:Kraft B Thermocell B Taircell B Munktell.The monolayer capacity value tends to decrease in the same sequence,i.e.from2.02to1.09mg g?1for Kraft and Munktell celluloses,respectively.

The results obtained give evidence that Munktell microcrystalline cellulose with the more ordered structure contains less reactive centers accessible for interaction with phosphoric acid compared to Thermocell.The same goes for Taircell cellulose and regenerated Kraft pulp,whose molecules have larger amounts of disordered microregions.

During cellulose impregnation and pretreatment changes of DP occur.As Munktell and Taircell differ essentially in terms of supramolecular structure and DP(Table1)they were chosen to compare the effect of pretreatment temperature on DP.

The hydrolytic effect of phosphoric acid on Taircell cellulose is noticeable already under impregnation conditions by a considerable decrease of DP(Table3).At pretreatment temperature of100°C and with3.5%phosphoric acid the process of hydrolysis of cellulose chains continues.However,when larger amounts(7%)of Table2

Hydrophilic properties of cellulose

Cellulose Monolayer Amount of adsorbed water(mg g?1)at the water vapor relative

pressure p/p0=0.98capacity(mg

g?1)

Munktell89.9 1.09

Thermocell155.2 1.86

Taircell177.2 1.89

Kraft pulp 2.02

195.2

G.Dobele et al./J.Anal.Appl.Pyrolysis58–59(2001)453–463

457

Table3

Changes of polymerization degree of impregnated celluloses

Cellulose Degree of polymerization Conditions of

Conditions of pretreatment(°C)

impregnation

3.5%H3PO4–

Taircell445

100310

160265(9a)

7%H3PO4

–

384

100380

160230(41a)

Munktell

3.5%H3PO4–

190

100200

380(10a)

160

7%H3PO4–

190

100

195

160320(43a)

a Amount(%)of cellulose insoluble in cadoxene.

acid is added,cellulose treated at100°C does not result in a further decline of DP (Table3).

Probably,by increasing the amount of phosphoric acid,reactions of intermolec-ular cross linkage might proceed and compete with cellulose hydrolysis.This assumption is based on literature data[12,13]which describe hydrolysis and intermolecular cross-linking of cellulose during heating in acid media as competing processes.Under similar conditions of impregnation and pretreatment,the DP of Munktell cellulose practically does not change and corresponds to the leveling-off degree for celluloses of about200.

As a result of thermal treatment at a higher temperature(160°C)approx.9–10% of cellulose was insoluble in cadoxene.This was observed both for Taircell and Munktell impregnated with3.5%of acid(Table3).At7%acid concentration the amount of the insolubles increased by a factor of4.

The DP of the soluble part of Taircell impregnated with3.5and7%of acid and at160°C tended to decrease to265and230,respectively.In contrast to

cellulose,the treatment at160°C for Munktell cellulose resulted in an increase in DP to380and320,for3.5and7%acid,respectively.This may be attributed to intermolecular condensation and/or formation of intermolecular cellu-lose phosphates.

The main product of fast pyrolysis of untreated celluloses is levoglucosan(LG) (Table4).Apart from LG,the volatile products of Munktell,Thermocell and Taircell celluloses contain about10%2-hydroxymethyl-5-hydroxy-2,3-dihydro-(4H)-pyran-4-one.Thermocell cellulose and recycled Kraft pulp are characterized by high contents of acetic acid in pyrolysis products of17.5and25.1%,respectively. Levoglucosenone(LGone)formation from these celluloses might be connected with the effect of compounds added during their production process.

458

G .Dobele et al ./J .Anal .Appl .Pyrolysis 58–59(2001)453–463

T a b l e 4V o l a t i l e p r o d u c t s o b t a i n e d d u r i n g p y r o l y s i s o f c e l l u l o s e s i n t h e a b s e n c e a n d p r e s e n c e o f p h o s p h o r i c a c i d (r e l .%)

I m p r e g n a t i o n a n d p r e t r e a t m e n t L G o n e 567L G

G +L G o n e

1a 2

C e l l u l o s e

0.21.00.62.710.381.582.51.0M u n k t e l l

1.8B l a n k 6.8

2.3

3.113.579.365.80.5

4.90.7+3.5%H 3P O 4

0.465.36.62.23.015.580.90.64.3100°C 5.21.71.89.082.873.70.5160°C 0.94.66.01.62.05.280.9+5%H 3P O 4

1.15.10.675.75.71.8

2.15.381.476.10.55.01.0100°C 0.670.26.52.22.58.578.81.15.5160°C 4.61.21.7

3.880.877.00.66.02.0+7%H 3P O 4

5.01.01.31.675.1100°C 1.7

6.40.773.55.11.41.61.2

79.6

78.3160°C

0.86.9

1.8

2.24.910.349.1T h e r m o c e l l

55.9B l a n k 17.46.90.46.87.41.72.716.179.162.90.4+3.5%H 3P O 4

0.86.27.10.92.315.680.8100°C 0.75.80.465.27.20.92.115.481.466.00.55.30.6160°C 0.466.77.01.22.114.681.40.65.4+5%H 3P O 4

7.31.41.712.879.967.105100°C 0.96.07.71.02.014.380.2160°C 0.85.60.665.97.00.21.39.882.873.00.55.20.9+7%H 3P O 4

7.30.31.35.580.6100°C 1.46.00.675.16.9

0.6

1.3

6.4

81.2

74.80.75.5

160°C

1.5

1.76.710.664.5T a i r c e l l

67.5B l a n k 3.44.54.23.07.91.73.032.281.749.50.43.40.4+3.5%H 3P O 4

6.81.21.86.680.9100°C 1.45.80.674.38.71.63.022.180.458.20.54.00.6160°C

7.71.22.414.480.9+5%H 3P O 4

1.04.40.566.58.51.6

2.615.579.964.30.54.71.1100°C 9.51.9

3.226.478.1160°C 0.9

4.30.751.66.41.63.38.578.469.90.7+7%H 3P O 4

1.45.68.11.9

2.911.985.4100°C 0.74.00.57

3.58.1

1.3

2.2

12.0

79.7

67.7

160°C 0.74.61.1

459

G .Dobele et al ./J .Anal .Appl .Pyrolysis 58–59(2001)453–463

T a b l e 4(C o n t i n u e d )

L G

C e l l u l o s e

G +L G o n e

I m p r e g n a t i o n a n d p r e t r e a t m e n t

1a 23L G o n e 2.16.27.941.83.547.35.45.825.0B l a n k K r a f t p u l p

0.556.37.71.12.421.878.11.56.3+3.5%H 3P O 4

9.71.22.220.475.454.9100°C 0.77.40.956.6160°C 9.21.22.720.176.70.96.00.761.4+5%H 3P O 4

7.61.52.215.576.90.57.90.69.20.72.118.674.856.10.78.11.3100°C 8.80.92.417.676.7160°C 1.26.70.859.07.21.12.29.676.266.60.88.11.7+7%H 3P O 4

1.059.77.70.51.416.075.7100°C

2.28.87.20.01.312.678.7

66.06.71.0160°C 1.9a

1,A c e t i c a c i d ;2,2-F u r f u r a l ;3,a -A n g e l i c a l a c t o n e ;5,1,4:3,6–D i -a n h y d r o -a -g l u c o p y r a n o s e ;6,5-H y d r o x y m e t h y l -2-f u r a l d e h y d e ;7,2-H y d r o x y m e t h y l -5-h y d r o x y -2,3-d i h y d r o -(4H )-p y r a n -4-o n e .

460G.Dobele et al./J.Anal.Appl.Pyrolysis58–59(2001)453–463 Interestingly,the total amount of LG and LGone for all celluloses varies within a narrow range of75–85%,regardless of the amount of phosphoric acid and pretreatment temperature(Table4).

An increase in the pretreatment temperature has only minor effects on the composition of volatiles from Munktell,Thermocell and Kraft celluloses(Figs.1 and2).In the case of Taircell the strongest effect of pretreatment temperature is observed when 3.5%of phosphoric acid was added.LGone formation has a maximum at a pretreatment temperature of100°C in agreement with the consider-able decrease of DP of Taircell after impregnation and pretreatment(Table3). The dehydrating action of phosphoric acid is demonstrated by the formation of

LGone,which yielded a maximum amount for the more ordered Munktell cellulose. Thus,at7%of phosphoric acid the volatile products of pyrolysis of this cellulose contain only a negligible amount of LG,which tends to decrease to1.2%as the

Fig.1.Variation in levoglucosenone content in volatiles depending on cellulose pretreatment tempera-tures.

461

G.Dobele et al./J.Anal.Appl.Pyrolysis58–59(2001)453–463

Fig.2.Variation in levoglucosan content in volatiles depending on cellulose pretreatment temperatures. pretreatment temperature increases up to160°C.In this case,the relative LGone content is78.3%.

In the case of pyrolysis of other celluloses LG yield is rather high even after addition of7%of phosphoric acid.This might be explained by a smaller breaking energy of the glycosidic bond in less ordered microregions.Hence,phosphoric acid catalyses mainly the splitting of the glycosidic bond.This process is accompanied by the release of non-dehydrated1,6-anhydrosaccharides.

The low content of non-dehydrated1,6-anhydrosaccharides in products of pyrol-ysis of Munktell cellulose might be connected with its low accessibility and the problems associated with the penetration of phosphoric acid into high ordered

regions.These are likely to exist as the crystallinity index is constant under

462G.Dobele et al./J.Anal.Appl.Pyrolysis58–59(2001)453–463

conditions of impregnation and thermal pretreatment.Therefore,the catalytic effect of phosphoric acid on depolymerization reactions occurs simultaneously with dehydration reactions after the breakdown of crystallites during pyrolysis.

The absence of LG in volatile products of cellulose slow pyrolysis[14]under conditions promoting the dehydration reactions,con?rms the propositions made on the basis of the obtained results.

For the preparative production of LGone with a higher yield,it is necessary to carefully select the cellulosic feedstocks taking into account their properties such as the supramolecular structure and degree of polymerization.

4.Conclusions

Impregnation of cellulose with an acidic catalyst such as phosphoric acid and heat treatment results in a decrease of DP by hydrolysis preferably in less ordered microregions of cellulose.However,evidence was found that heating also gives rise to intermolecular cross-linking reactions leading to a decrease in the total yield of volatiles.The degree of development by dehydration reactions leading to the formation of levoglucosenone depends on the cellulose crystallinity and thus the accessibility for the acidic catalyst.Highly ordered celluloses favor the forma-tion of levoglucosenone whereas celluloses with a higher amount of less ordered regions show also parallel formation of levoglucosan.

Acknowledgements

The work was?nancially supported by the Latvian Republic grant No.588and through the bilateral co-operation programme between the German Ministry of Food,Agriculture and Forestry(BML)and Latvia,Az.624-0099-LET. References

[1]D.Radlein,Pyrolysis Network for Europe4(1997)4.

[2]G.Dobele,G.Rossinskaja,G.Telysheva,D.Meier,O.Faix,J.Anal.Appl.Pyrolysis49(1999)

307.

[3]Z.J.Witczak,in:Z.J.Witczak(Ed.),Levoglucosenone and Levoglucosans,Chemistry and Applica-

tion,ATL,1994,p.4.

[4]G.Dobele,G.Rossinskaja,B.Rone,in:J.F.Kennedy,P.A.Williams(Eds.),The Chemistry and

Processing of Wood and Plant Fibrous Materials,Woodhead,Cambridge,1996,p.345.

[5]M.Lewin,A.Bash,Flame Retard.Polym.Mater.2(1978)1.

[6]B.Rone,G.Domburg,Khimiya Drev.6(1985)65.

[7]https://www.wendangku.net/doc/e315056452.html,ka,S.A.Chernyavskaya,https://www.wendangku.net/doc/e315056452.html,posite Mater.32(1996)549.

[8]M.Ioelovich,A.Tupureine,G.Veveris,Khimija Drev.5(1989)

[9]L.Bolotnikova,S.Danilov,T.Samsonova,Zhurn.Prikl.Khim.39(1966)176.

[10]D.Meier,O.Faix,in:S.Y.Lin,C.W.Dence(Eds.),Methods in Lignin Chemistry,Springer,Berlin,

1992,p.177.

463

G.Dobele et al./J.Anal.Appl.Pyrolysis58–59(2001)453–463

[11]E.Back,Cross-linking in cellulose products at elevated temperatures,in:Third Fundamental

Research Symposium,1965,p.545.

[12]K.Kishore,K.Mohandas,Fire and Materials6(2)(1982)54.

[13]I.N.Jermolenko,I.P.Ljubliner,N.V.Gulko.Element-containing Carbon Fibrous Materials,

Nauka i Technika Minsk(1982)272.

[14]G.Rossinskaja,G.Dobele,G.Domburg,Khimiya Drev.1(1986)73.

会计审计英语词汇大全

1 ability to perform the work能力履行工作 2 acceptance procedures承兑程序过程 3 accountability经管责任,问责性 4 accounting estimate会计估计 5 accounts receivable listing应收帐款挂牌 6 accounts receivable应收账款 7 accruals listing应计项目挂牌 8 accruals应计项目 9 accuracy准确性 10 adverse opinion否定意见 11 aged analysis年老的分析（法,学）研究 12 agents代理人 13 agreed-upon procedures约定审查业务 14 analysis of errors错误的分析（法,学）研究 15 anomalous error反常的错误 16 appointment ethics任命伦理学 17 appointment任命 18 associated firms联合的坚挺 19 association of chartered certified accounts（ACCA）特计的证（经执业的结社（ACCA） 20 assurance engagement保证债务

21 assurance保证 22 audit审计,审核,核数 23 audit acceptance审计承兑 24 audit approach审计靠近 25 audit committee审计委员会,审计小组 26 ahudit engagement审计业务约定书 27 audit evaluation审计评价 28 audit evidence审计证据 29 audit plan审计计划 30 audit program审计程序 31 audit report as a means of communication审计报告如一个通讯方法32 audit report审计报告 33 audit risk审计风险 34 audit sampling审计抽样 35 audit staffing审计工作人员 36 audit timing审计定时 37 audit trail审计线索 38 auditing standards审计准则 39 auditors duty of care审计（查帐）员的抚养责任 40 auditors report审计报告 41 authority attached to ISAs代理权附上到国际砂糖协定

DATA_README CMEM模型最精简的解析手册

NCHRP PROJECT 25-11 VEHICLE EMISSIONS DATABASE INTRODUCTION An extensive vehicle emissions testing program was conducted from April 1996 to September 1998 at the College of Engineering-Center for Environmental Research and Technology (CE-CERT) at the University of California Riverside. This program was carried out as part of a four-year project sponsored by the National Cooperative Highway Research Program (NCHRP, Project 25-11) to create and verify a comprehensive modal emission model. Details of the overall project can be found in the CMEM User’s Guide and (forthcoming) NCHRP Project 25-11 Final Report. In the first phase of the vehicle-testing program, a total of 327 vehicle tests were performed over 18 months. Of the 327 vehicle tests, 315 of the data sets are considered valid and are included on this CD. In the fourth phase of the test program an additional 31 vehicles were tested and are included in this database (test numbers 400 and above). Vehicles were typically tested over three test cycles: the 3-bag FTP (Federal Test Procedure), the US06 cycle (Bag 4 of the Supplemental FTP), and an in-house designed modal emission cycle, MEC. The FTP cycle is part of the standard certification test procedure and provides baseline information about a vehicle’s emissions which can be used as a reference when comparing with existing vehicle tests. The FTP test data also provides cold and warm start information. The high speed US06 test cycle targets “off-cycle”, non-FTP operation that is more characteristic of modern driving patterns. The modal emission cycle (MEC) was specially designed and included to provide emission data that can more easily be matched to specific driving modes: various steady-state cruise speeds, accelerations, decelerations, and idle. Vehicle testing was performed by CE-CERT’s Vehicle Emission Research Laboratory (VERL) and were processed and recorded by CE-CERT’s Transportation Systems Research (TSR) group. Vehicle test data sets are referred to by their TSR assigned test number. The raw emission data were post-processed and validated. The raw emission data from VERL were received as concentration values and subsequently converted from gas concentrations in parts-per-million (ppm) to a mass emission rate in grams per second. This was done using algorithms for the dynamometer and gas analyzers which must account for parameters such as emission densities, exhaust flow rates, and differences in dry and wet gas measurements. The equations and procedure used to account for such factors are given in Appendix B of the NCHRP Project 25-11 Final Report. For both post-processing procedures, the post-processed modal data were appended to a log file which also includes the vehicle name, cumulative modal emission rates in grams per mile for CO2, CO, HC, and NOx and comparable integrated emission results obtained by the bag analyses. The final step for all the test data is comparing the cumulative modal and integrated bag results as well as making visual checks to determine the need for any more post-processing of the data.

审计术语

审计术语(英汉) 2009-5-20 16:3【大中小】【打印】【我要纠错】 audit 审计 CPA 注册会计师 assurance 可信性保证 audit of financial statements 财务报表审计 agreed-upon procedures 执行商定程序 compilation 编制 high levels of assurance 高保证水平 moderate levels of assurance 中等保证水平 credibility 可信性、可信程序 reliability 可靠性、可靠程序 relevance 相关、相关性 continuing professional education（CPE）职业后续教育 A uniform CPA examination 统一注册会计师考试 professional skepticism 职业谨慎 objectivity 客观，客观性 professional competence 专业胜任能力 Senior/CPA-in-charge 项目经理 audit engagement letter 业务约定书 recurring audit 连续审计、常年审计 the client 委托人 the nominated CPA 被提名审计师 change CPA 更换审计师 the exsiting CPA 现任审计师

the preceding CPA（The predecessor CPA 后任会计师 audit appointment 审计委托 the agreed term 约定条款 accpet an audit engaement 接受业务委托 the objective of the engaement 委托目的 the scope of the audit 审计范围 issue the audit report 出具审计报告 other CPA 其他注册会计师 expert 专家 withdraw 撤销 an initial audit 初次审计 the board of directors 董事会 a change in engaement 变更约定书 shareholder 股东 component 组成部分 knowledge of the entity's business 了解补审计单位情况 performing an audit of financial statements 实施财务报表审计 assess inherent and control risks 评估固有风险和内部控制风险determine the nature， timing and extend of the audit procedures 决定审计程序的性质、时间和范围 a general knowledge of …， a preminary knowledge of 初步了解 a more particular knowledge of 进一步了解 prior to accepting an engagement 接受业务委托之前 following acceptance of the engagement 接受业务委托之后 update and revaluate information gathered previously 更新并重新评价以前收集的信息

RsLogix5000 读取ProLinx DFNT数据的方法

RsLogix5000 读取ProLinx DFNT数据的方法 1、MSG指令说明 2、由上图可得，ProLinx数据库具有4000个供用户使用的寄存器，分别编号为0---3999；对于ControlLogix PLC在做MSG指令的时候，我们可以使用PCCC方式和CIP方式，建议使用CIP方式；因此采用CIP方式时数据库0—3999对应的地址分别为Int_data[0]到Int[3999]。 3、建立MSG读指令 3.1 指令建立后点击设置按钮，会弹出下面的MSG指令设置窗口：

Message Type：设置Message类型，本例设置为CIP Data Table Read Source Element ：该参数设置从ProLinx那个寄存器开始读取，图中所示为从第一个寄存器开始读取。 Number of Elements：该参数设置读取多少个数据，图中所示为100个 Destination Elements：该参数设置读取过来的数据存放到Controller Tags中的哪个标签，本例设置为ReadData_PLX[0]，该标签为一个100个int类型的数组。！！！：该MESSAGE执行的结果是将ProLinx里的0-99这100个寄存器的数据读到 ControlLogix标签ReadData_PLX[0]到ReadData_PLX[99]。 3.2 设置通讯路径，设置完Configuration界面后，点击Communication菜单进入通讯路径设置界面如下： Path：ENBT为本地的1756-ENBT模块作为源设备 2说明本次MSG采用的是EtherNet/IP模式 192.168.0.1为ProLinx的IP地址设置完毕点击确定保存即可。 4、写数据的过程同上，Message Type：设置为CIP Data Tabel Write Source elements：为ControlLogix控制器内标签 Destination elements：目的数据为Prolinx寄存器对应地址 Number of elements：为往下写的数据。 Path：配置同上。

(完整版)审计常用英文词汇

审计常用英文词汇 1.Assurance engagements and external audit 鉴证业务和外部审计 Materiality，true and fair presentation，reasonable assurance 重要性，真实、公允反映，合理保证 Appointment，removal and resignation of auditors 注册会计师的聘用，解聘和辞职 Types of opinion：unmodified opinion，modified opinion，adverse opinion，disclaimer of opinion 审计意见类型：无保留意见，保留意见，否定意见，无法表示意见 Professional ethics：independence，objectivity，integrity，professional competence，due care，confidentiality， professional behavior 职业道德：独立、客观和公正，专业胜任能力，应有的关注，保密性，职业行为 Engagement letter 审计业务约定书 2.Planning and risk assessment 审计计划和风险评估 General principles 一般原则 Plan and perform audits with an attitude of professional skepticism 计划和执行审计业务应保持应有的职业怀疑态度 Audit risks = inherent risk ×control risk ×detection risk 审计风险=固有风险×控制风险×检查风险 Risk-based approach 风险导向型审计 Understanding the entity and knowledge of the business 了解被审单位 Assessing the risks of material misstatement and fraud 估计重大错报或舞弊的风险 Materiality （level），tolerable error 重要性水平，可容忍误差 Analytical procedures 分析性复核程序 Planning an audit 制定审计计划 Audit documentation：working papers 审计记录：工作底稿 The work of others 利用其他人的工作 Rely on the work of experts 利用专家工作 Rely on the work of internal audit

市场营销学练习与思考题国教版xxxx0506readdatajsp.doc

练习与思考题一、单选１、商品和劳务以转售或租给他人获取利润的个人或组织构成 A、消费者市场Ｂ、生产者市场Ｃ、中间商市场Ｄ、政府市场 2、以“顾客需要什么，我们就生产什么”作为其座右铭的企业是企业。 A、生产导向型 B、推销导向型 C、市场营销导向型 D、社会营销导向型 3、企业感知外部世界的常用手段是。 A、公共关系 B、市场营销 C、倾听 D、市场调研 4、是指企业利用多种信息载体，与目标市场进行沟通的传播活动，包括广告、人员推销、营业推广与公共关系等。 A、产品 B、定价 C、促销 D、分销 5、市场营销环境是指企业营销职能外部的因素和力量，包括宏观环境和微观环境。 A、可改变 B、不可捉摸 C、可控制 D、不可控制 6、消费者的购后评价主要取决于。 A、心理因素 B、产品质量和性能 C、付款方式 D、服务态度 7、组织市场需求的波动幅度消费者市场需求的波动幅度。 A、小于 B、大于 C、等于 D、都不是 8、同一细分市场的顾客需求具有。 A、绝对的共同性 B、较多的共同性 C、较少的共同性 D、较多的差异性 9、处于导入期的新产品，消费者对其不熟悉，竞争者也较少，这时偏向于采用 A、无差异性营销策略 B、差异性营销策略 C、集中性营销策略 D、市场细分策略 10、当产品市场需求富有弹性且生产成本和经营费用随着生产经营规模的增加而下降时，企业便具备了的可能性。 A、渗透定价 B、撇脂定价 C、萎缩定价 D、招徕定价 11、市场营销学诞生于20世纪初的。 A、欧洲 B、日本 C、美国 D、中国 12、市场营销学“革命”的标志是提出了的观念。 A、以消费者为中心 B、以生产者为中心 C、市场营销组合 D、网络营销

常用审计英语词汇

常用审计英语词汇 1 ability to perform the work 能力履行工作 2 acceptance procedures 接受程序 3 accountability 经管责任,问责性 4 accounting estimate 会计估计 5 accounts receivable listing 应收账款列表 6 accounts receivable 应收账款 7 accruals listing 应计项目列表 8 accruals 应计项目 9 accuracy 准确性 10 adverse opinion 否定意见 11 aged analysis 账龄分析 12 agents 代理人 13 agreed-upon procedures 约定审查业务 14 analysis of errors 错误分析 15 anomalous error 反常的错误 16 appointment ethics 接受任命的相关职业道德考虑 17 appointment 任命 18 associated firms 关联公司 19 association of chartered certified accounts（ACCA）英国特许注册会计师公会 20 assurance engagement 保证约定

21 assurance 保证 22 audit 审计,审核,核数 23 audit acceptance 接受审计 24 audit approach 审计方法 25 audit committee 审计委员会,审计小组 26 audit engagement 审计业务约定书 27 audit evaluation 审计评价 28 audit evidence 审计证据 29 audit plan 审计计划 30 audit program 审计程序 31 audit report as a means of communication 作为沟通方式的审计报告 32 audit report 审计报告 33 audit risk 审计风险 34 audit sampling 审计抽样 35 audit staffing 审计工作人员调配 36 audit timing 审计时间安排 37 audit trail 审计线索 38 auditing standards 审计准则 39 auditors duty of care 审计人员的审慎职责 40 auditors report 审计报告 41 authority attached to ISAs 遵守国际审计准则

审计词汇表

●audit 审计 ●attestation 鉴证 ●audit of financial statements 财务报表审计 ●high levels of assurance 高水平保证 ●compilation 编制 ●reliability 可靠性 ●relevance 相关性 ●1professional skepticism 职业谨慎 ●objectivity 客观性 ●professional competence 专业胜任能力 ●audit engagement letter 业务约定书 ●the client 委托人 ●the existing CPA 现任注册会计师 ●the successor CPA 后任注册会计师 ●the preceding CPA前任注册会计师 ●issue the audit report 出具审计报告 ●expert 专家 ●the board of directors 董事会 ●determine the nature， timing and extent of the audit procedures 确定审计程序的性质、时间和范围 ● a general knowledge of ——初步了解―――的情况 ● a more knowledge of——进一步了解的情况 ●the prior year’s working papers 以前年度工作底稿 ●minutes of meeting 会议纪要 ●business risks 经营风险 ●accounting estimate 会计估计 ●management representations 管理层声明 ●going concern assumption 持续经营假设 ●audit plan 审计计划 ●error 错误 ●fraud舞弊 ●misappropriation of assets 侵占资产 ●materiality 重要性 ●misstatements or omissions 错报或漏报 ●subsequent events 期后事项 ●audit risk 审计风险 ●detection risk 检查风险 ●inappropriate audit opinion 不适当的审计意见

常用审计英语术语

accounting estimate 会计估计 accounts receivable 应收账款 accruals listing 应计项目挂牌 accruals 应计项目 accuracy 准确性 adverse opinion 否定意见 agreed-upon procedures 约定审查业务 analysis of errors 错误的分析（法,学）研究anomalous error 反常的错误 association of chartered certified accounts（ACCA）assurance engagement 保证约定 assurance 保证 audit 审计,审核,核数 audit acceptance 审计承兑 audit approach 审计靠近 audit committee 审计委员会,审计小组 audit engagement 审计业务约定书 audit evaluation 审计评价 audit evidence 审计证据 audit plan 审计计划 audit program 审计程序 audit report 审计报告 audit risk 审计风险 audit sampling 审计抽样 audit staffing 审计工作人员 audit timing 审计定时 audit trail 审计线索 auditing standards 审计准则 auditors report 审计报告 bad debts 坏账 bank 银行 bank reconciliation 银行对账单,余额调节表beneficial interests 受益权 business risk 经营风险 cash count 现金盘点 confidence 信任 confidentiality 保密性 confirmation of accounts receivable 应收账款的查证conflict of interest 利益冲突 contingent asset 或有资产 contingent liability 或有负债 control environment 控制环境 control procedures 控制程序 control risk 控制风险

审计英文词汇整理

1.audit 审计 2.attestation 鉴证 3.credibility 可信赖程度 4.audit of financial statements 财务报表审计 5.agreed-upon procedures 执行商定程序 6.high levels of assurance 高水平保证 https://www.wendangku.net/doc/e315056452.html,pilation 编制 8.reliability 可靠性 9.relevance 相关性 10.professional skepticism 职业谨慎 11.objectivity 客观性 12. professional competence 专业胜任能力 13.Senior/CPA-in-charge 项目经理 14.audit engagement letter 业务约定书 15.recurring audit 连续审计 16.the client 委托人 17.change CPA更换注册会计师 18.the existing CPA 现任注册会计师 19.the successor CPA 后任注册会计师 20.the preceding CPA前任注册会计师 21.issue the audit report 出具审计报告 22.expert 专家 23.the board of directors 董事会 24.knowledge of the entity‘ s business 了解被审计单位情况 25.assess material misstatement risks评估重大错报风险 26.detemine the nature，timing and extent of the audit procedures 确定审计程序的性质、时间和范围 27.a general knowledge of 初步了解―――的情况 28.a more knowledge of 进一步了解的情况 29.the prior year‘s working papers 以前年度工作底稿 30.minutes of meeting 会议纪要 31.business risks 经营风险 32.appropriateness适当性 33.accounting estimate 会计估计 34.management representations 管理层声明 35.going concern assumption 持续经营假设 36.audit plan 审计计划 37.significant audit areas 重点审计领域 38.error 错误 39.fraud舞弊 40.modified or additional procedures 修改或追加审计程序 41.misappropriation of assets 侵占资产42.transactions without substance 虚假交易 43.unusual pressures 异常压力 44.the suspected noncompliance 涉嫌存在违法行为 45.materialiy 重要性 46.exceed the materiality level 超过重要性水平 47.approach the materiality level 接近重要性水平 48.an acceptably low level 可接受水平 49.the overall financial statement level and in related account balances and transaction levels 财务报表层和相关账户、交易层 50.misstatements or omissions 错报或漏报 51.aggregate 总计 52.subsequent events 期后事项 53.adjust the financial statements 调整财务报表 54.perform additional audit procedures 实施追加的审计程序 55.audit risk 审计风险 56.detection risk 检查风险 57.inappropriate audit opinion 不适当的审计意见 58.material misstatement 重大的错报 59.tolerable misstatement 可容忍错报 60.the acceptable level of detection risk 可接受的检查风险 61.assessed level of material misstatement risk 重大错报风险的评估水平 62.simall business 小规模企业 63.accounting system 会计系统 64.test of control 控制测试 65.walk-through test 穿行测试 https://www.wendangku.net/doc/e315056452.html,munication沟通 67.flowchart 流程图 68.reperformance of internal control 重新执行 69.audit evidence 审计证据 70.substantive procedures 实质性程序 71.assertions认定 72.esistence存在 73.occurrence发生 https://www.wendangku.net/doc/e315056452.html,pleteness完整性 75.rightsand obligations 权利和义务 76.valuationand allocation 计价和分摊 77.cutoff截止 78.accuracy准确性 79.classification分类 80.inspection检查 81.supervision of counting 监盘 82.observation观察

存储器设计：存储器设计课程设计

计算机组成原理实验实验五存储器设计专业班级计算机科学与技术学号0936008 姓名冯帆学号0936036 姓名张琪实验地点理工楼901 实验五存储器设计一、实验目的 1、掌握RAM 和ROM 的Verilog 语言描述方法； 2、学习用宏模块的方法定制RAM 和ROM 。二、实验内容

1、设计并实现一个8*8 的单端口的RAM ； 2、设计并实现一个128*16的ROM ； 3、设计并实现一个双端口的128*16的RAM 。 4、设计并实现正弦信号发生器，参考“正弦信号发生器实验指南”。三、实验仪器及设备 PC 机+ Quartus Ⅱ0 + DE2-70 四、实验步骤打开Quartus 软件，新建工程。 2．分析单端口，双端口，ROM,RAM 的含义。 3．Verilog 程序如下，并简单注释。 ①

module SingleRamTest(read_data, read_address, write_data, write_address, memwrite, clock, reset); output [7:0] read_data; //数据的输出 input [2:0] read_address; //读数据地址的输入 input [7:0] write_data; //写数据地址的输入 input [2:0] write_address; //写数据地址的输入 input memwrite; //若该信号为1，进行写操作，反之，写操作input clock; input reset; //复位和时钟信号 reg [7:0] read_data, mem0, mem1,mem2,mem3,mem4,mem5,mem6,mem7; //设置存储器存储单元 always @(read_address or mem0 or mem1 or mem2 or mem3 or mem4 or mem5 or mem6 or mem7) //若上述信号有一个发生变化，则启动该模块begin

常用审计英语词汇

常用审计英语词汇 1.ability to perform the work 能力履行工作 2.acceptance procedures 承兑程序过程 3.accountability 经管责任 4.accounting estimate 会计估计 6.accounts receivable 应收账款 7.accruals listing 应计项目挂牌 8.accruals 应计项目 9.adverse opinion 否定意见 10.agreed-upon procedures 约定审查业务 11.analysis of errors 错误的分析（法,学）研究 12.anomalous error 反常的错误 13.appointment ethics 任命伦理学

14.assurance engagement 保证约定 15.assurance 保证 16.audit 审计，审核，核数 17.audit acceptance 审计承兑 18.audit approach 审计靠近 19.audit committee 审计委员会，审计小组 20.audit engagement 审计业务约定书 21.audit evaluation 审计评价 22.audit evidence 审计证据 23.audit plan 审计计划 24.audit program 审计程序 25.audit report 审计报告

26.audit risk 审计风险 27.audit sampling 审计抽样 28.audit staffing 审计工作人员 29.audit timing 审计定时 30.audit trail 审计线索 31.auditing standards 审计准则 32.auditors duty of care 审计（查账）员的责任 33.auditors report 审计报告 34.automated working papers 自动化工作文件 35.bad debts 坏账 36.bank reconciliation 银行对账单，余额调节表 37.beneficial interests 受益权 38.best value 最好的价值

审计常用术语及外文

审计常用术语审计术语英语四大”会计师事务所：普华永道Princewater - houseCoopers 安永Ernst & Young 毕马威KPMG 德勤Deloitte Touche Tohmatsu 安达信Arthur Anderson 安然Enron 世通worldcom 国际机构的名称：：国际会计师联合会IFAC 国际会计师联合会下设的国际审计和鉴证准则理事会美国注册会计师协会AICPA 中国注册会 IAASB 计师协会CICPA 审计audit 内部审计internal audit 政府审计public sector audit 账项基础审计accounting number-based audit 风险导向审计方法risk-oriented audit approach 其他鉴证业务audit related services 审阅业务review 有限责任公司制limited liability companies, LLCs 有限责任合伙制limited liability partnerships, LLPs 注册会计师职业道德规范code of ethics for professional accountants Rules of professional conduct 独立independence 客观objectivity 公正integrity

专业胜任能力professional competence 应有关注due care 保密confidentiality confidence 职业行为professional conduct 技术准贝U technical standards 保持实质上的独立和形式上的独立 The member is, and is seen to be independent 费用fee 佣金commission 经济利益interest 经济利益的冲突conflicts of interest 舞弊fraud: refers to intentional acts which may involve the falsification of documents and records, the misappropriation of assets, or misapplication of accounting policies. 差琴昔error: refers to the unintentional misapplication of accounting policies, oversights or misinterpretations of fact and clerical errors. 更换会计师事务所Changes in professional appointments 国际趋同global convergence /international convergence 鉴证业务assurance services 全面质量管理quality control of audit Enforce the ethical guidance

fifo_read

/******************************************************** 说明：1、该模块是自定义的fifo读操作控制器 2、avalon总线信号，每次操作时仅维持一个时钟周期 3、读操作有两个时钟的等待 4、状态读的是fifo的usedw，位数可调，默认6bit 5、fifo外设的数据位数可调，默认12bit ********************************************************/ module fifo_read_avalon( clk, reset_n, chipselect, byteenable, address, read, readdata, write, writedata, //fifo接口 q, empty, usedw, rdreq,//读缓存fifo数据，rd=‘0’时开始读 flag,//rd为0标志 wrreq, //ad控制口 cs_control,//写通道使能控制cs为低，写通道 wr_control,//写启动转换wr=0 channel_address ); parameter bits_of_q=16; parameter bits_of_usedw=8; input clk;//总线时钟 input reset_n;//总线复位 input chipselect;//片选 input[1:0]address;//地址线 input read;//读请求 output[31:0]readdata;//读数据 input write;//写请求 input[31:0]writedata;//写数据 input[3:0]byteenable;

审计专业词汇中英对照

audit evidence 审计证据audit program 审计方案 audit procedures 审计程序competence 适当性 sufficiency 充分性combined effect 联合效应persuasiveness 说服力relevance 相关性effectiveness 有效性objectivity 客观性timeliness 及时性physical evidence 实物证据confirmation evidence 函证证据documentation evidence 书面证据analytical procedures 分析程序获得的数据inquires of the client 询问客户获得的证据reperformance evidence 重新执行获得的证据observation evidence 观察获得的证据auditing standards 审计准则sample size 样本规模 accounts receivable 应收账款notes receivable 应收票据 liabilities 负债advances from customers 客户预付款mortgages payable 应付抵押账款bonds payable 应付债券 owners’ equity 所有者权益creditor 债权人 lender 借款人mortgagor 抵押人 bondholder 债券持有人shares outstanding 发行在外股份contingent liabilities 或有负债examine 检查 scan 浏览read 阅读 recomputed 重新计算foot 加总 trace 追查compare 比较 count 盘点observe 观察 inquire 询问vouch 核对 audit documentation 审计档案audit files 审计文件 audit working papers 审计工作底稿interest receivable 应收利息permanent files 永久文件working trial balance 试算平衡草稿adjusting and reclassification entries 调整分录及重分类分录 supporting schedules 支持性档案cash count sheet 现金盘点表 bank reconciliation 银行存款余额调节表trial balance/list 试算平衡表（列表）reconciliation of amounts 金额调节表acceptable audit risk 可接受审计风险inherent risk 固有风险business risk 经营风险analytical procedures 分析程序materiality 重要性水平 control risk 控制风险fraud risks 舞弊风险 directors 董事会the audit committee 审计委员会corporate charter and bylaws 公司章程与规章meeting minutes 会议记录 material misstatements 重大错报enterprise risk management 企业风险管理short-term debate-paying ability 短期偿债能力current ratio 流动比率 liquidity activity ratio 流动性比率inventory turnover 存货周转率 long-term obligation 长期义务debt to equity 债务权益比profitability ratio 盈利能力比率profit margin 利润率 planning phase 计划阶段going concern 持续经营能detailed test 细节测试testing phase 测试阶段completion 完成阶段gross margin 毛利率 cash ratio 现金比率quick ratio 速动比率accounts receivable turnover 应收账款周转率debt to equity 债务权益比