MODELING THE RELIABILITY OF INFORMATION MANAGEMENT SYSTEMS BASED ON MISSION SPECIFIC TOOLS SET SOFTWARE

Transcription

1 Knowledge Dynamcs MODELING THE ELIABILITY OF INFOMATION MANAGEMENT SYSTEMS BASED ON MISSION SPECIFIC TOOLS SET SOFTWAE Cezar VASILESCU Assocate Professor, egonal Department of Defense esources Management Studes, Natonal Defense Unversty, Bucharest, omana E-mal: Abstract: The operatonal envronments n whch nformaton management systems operate determne the exstence of complex stuatons. Consequently, the command and control flow can take dfferent paths, whch nvolve dfferent sets of actvtes. Each of those actvtes s assocated wth a specfc software applcaton set, known as Applcaton Software Tools (s). An operatonal profle represents a sequence of specfc processng of dstnct actvtes (from a functonal pont of vew), based on specfc Applcaton Software Tools and wth a certan tme lmt nterval. Each operatonal profle has assocated a probablty of occurrence. Each actvty s performed durng a specfed perod of tme, wth specfc sets of s. Totalty resultng specfcaton due to operatonal profles crowd formed a msson specfc software applcaton system, also known as a Msson Specfc Tools Set (MSTS). Each MSTS s element fulfll functons that meet the correspondng command and control actvtes, found n the form of lsts of features of the system operatonal profle. The am of ths paper s to present an orgnal MSTS relablty model, whch combnes the modellng approach based on operatonal profles wth ome esearch Laboratory software relablty modelng methodology. In ths way, t was realzed a representaton of applcaton set s relablty that quantfes ts level of relablty and also the assocated weghts of each applcaton. The fnal goal was to offer an adequate bass for the process of relablty growth. Ths paper s also gong to provde a calculus example of MSTS system relablty usng a representatve U.S. Navy C4IS system s combat acton (Tme Crtcal Targetng). The case study demonstrates the valdty and the usefulness of the model n order to ncrease the system s relablty. Key words: elablty modelng; Increase of software applcatons relablty; Operatonal profles; Applcaton software tools; Msson Specfc Tools Set 4

2 Knowledge Dynamcs Introducton Informaton management systems realze the processng of specfc nformaton necessary to conduct modern battlefeld complex command and control actvtes, n order to ensure the success n battle. For msson-orented software development t s necessary the modularzaton of the command and control actvtes and sub actvtes. Generally, the operatonal profle can be defned as a quanttatve characterzaton of the software usage, dependng on the nput space values. A profle conssts of an ndependent possbltes set and ther assocated occurrence probabltes [6]. The operatonal envronments n whch nformaton management systems operate determne the exstence of complex stuatons, characterzed by a great dversty of nformaton, nputs, actualzaton operatons etc. Consequently, the command and control flow can take dfferent paths, whch nvolve dfferent sets of actvtes. Each of those actvtes s assocated wth a specfc software applcaton set, known as Applcaton Software Tools (s). Speakng about nformaton management systems, an operatonal profle represents a sequence of specfc processng of dstnct actvtes (from a functonal pont of vew), based on specfc Applcaton Software Tools and wth a certan tme lmt nterval. Each operatonal profle has assocated a probablty of occurrence. Each actvty s performed durng a specfed perod of tme, wth specfc sets of s. Totalty resultng specfcaton due to operatonal profles crowd formed a msson specfc software applcaton system, also known as a Msson Specfc Tools Set (MSTS). Each MSTS s element fulfll functons that meet the correspondng command and control actvtes, found n the form of lsts of features of the system operatonal profle. Calculaton of MSTS system relablty wll be subject to of followng paragraph. Calculaton of MSTS system relablty MSTS system relablty predcton and growth requres a core computng. Ths approach s drven by the possblty of jont actvtes under dfferent dstnct operatonal profles. The calculaton relatons are: N = P MSTS pk k () k = n whch p k - Occurrence probablty of the k operatonal profle; k - elablty of the k operatonal profle; N P - Number of operatonal profles. The frst relatonshp s based on the fact that each operatonal profle s assocated wth an occurrence probablty [2]. Notaton 42

3 Knowledge Dynamcs { ; =, N } ( k) { belongs to the k profle} executon n the profle; = = the set of MST actvtes; =, ranked n ascendng order of ; = { : s an nstrument of the MSTS} ( ) = { ϕ : serves } ϕ ; ϕ ; = specfc software applcaton sets. Then k = n whch ( k ) " ' ( t t ) ' t = the begnnng moment of actvty ; " t = the endng moment of actvty. and where where λ " ' " ' ( t t ) = ( t t ) ϕ ( ) " ' " ' λ ( ) ( t t ) t t e = " ' ( t t ) = λ (4) The second calculaton relaton of MSTS system relablty s: N = P MSTS k k = can be transformed as * MSTS = ϕ n whch to the same. Note: * = (2) () (4bs) ( ) * s the product of all factors n the formula ( ) that correspond n case the appears one tme n the formula ( ) and * *, < otherwse. Ths sm s needed when profles nclude jont actvtes. Usng the frst formula for calculatng the relablty MSTS (n whch components may occur several tmes) can provde the specfcaton requrements for MSTS system relablty assessment and correspondence wth the relablty requrements []. (5) 4

4 Knowledge Dynamcs Also, MSTS system relablty calculaton usng the second relaton ( MSTS ) provdes the possblty to organze the process of relablty growth, to meet the requrements specfed. Thus n the calculaton of relablty can be calculated weghts ( Π ) assocated wth and determned ther nfluence. = ln * / ln MSTS (6) followed by the ncreasng orderng of the resultng strng of weghts { Π ϕ} :, to hghlght the order of prortes n addressng the growth of MSTS relablty. In ths way can be hghlghted MSTS components unsatsfactory n terms of relablty, so gvng a good support to system software desgners to eventually redesgn t (f requred) n the process of relablty growth. In what follows, we present an example of calculatng the MSTS system relablty, for the most common case n practcal operaton of the nformaton management systems, n whch under dfferent operatonal profles are common jont actvtes. Case study Dependng on the nature, sze and membershp of the nformaton management systems to a category of forces or other, command and control actvtes can have a hgh degree of specfcty. In [] there have been lsted a number of typcal command and control actvtes, and the general categores from whch they belong. Also, n case of large nformaton management systems analyss (e.g. natonal level), dentfcaton and analyss of all actvtes can be dffcult. For ths reason, we calculate the MSTS system relablty [4] usng for example one of the U.S. Navy C4IS system s combat acton. For ths, t s necessary a bref overvew of the C4IS system and command and control actvtes related to combat acton Tme Crtcal Targetng [5]. U.S. Navy uses varous systems aganst naval and ar targets, wth dfferent C4IS systems provdng gudance. The flow of actvtes nvolved was analyzed, n order to optmze command and control actvtes, elmnate the overlappng functonalty and ensure nteroperablty of systems. Table. The man command and control sub actvtes, related wth the combat acton Tme Crtcal Targetng Current ssue Name.. Analyss of survellance and reconnassance data lst 2.. econcle target combat prortes 2.2. Determne sensor avalablty 2.. Task sensor 2.4. Collect data.. Detect target.2. Determne envronment.. Trackng and postonng the target 44

5 Knowledge Dynamcs Current ssue Name.4. Identfyng target 4.. Update target lst 4.2. Assess engagement capablty 4.. Assgn weapon-target Platform selecton 4.4. Update msson plans 4.5. Perform TCT (tme crtcal target) deconflcton 5.. Execute force order 5.2. Support weapon flyout 5.. Fghtng target 6.. Collect nformaton on damage 6.2. Damage nformaton assessment 6. emove objectve from target lst The flow of command and control actvtes related to combat acton Tme Crtcal Targetng (accordng to Table ) s shown n Fgure Analyss of survellance and reco nnassance data lst econcle target co mba t prortes Determne sensor avalablty Ta sk sensor 4. Update target lst Collect data Detect target Determne envro nment. Trackng / postonng the target Identfyng target.4 Ass ess engagement capablty Collect nformaton on damage Assgn weapontarget Platform selecton Damage nformaton assessment Perform TCT deconfl cton Update msso n pl ans emove objectve from target lst Execute force order Support weapon flyout Fghtng target Fgure. Scenaro of C2 sub actvtes related to Tme Crtcal Targetng combat acton names assocated wth sub actvtes are not relevant to the proposed goals. We present n terms of quantty the correlaton between sub-c4is actvtes contaned n Fgure and the number of software modules provdng support to ther deployment (Fgure 2). Typcally, each operatonal profle of C4IS actvtes s a chan of sequental actons. Applcaton software tools sets are executed sequentally and/or compettve (exts a set representng the nput for another set). 45

6 Knowledge Dynamcs Number of software modules Sub-C4IS actvtes Fgure 2. Graph of the number of software modules provdng support to consstng subactvtes of Tme Crtcal Targetng actvty We analyze the scenaro of C4IS sub actvtes related to Tme Crtcal Targetng combat acton (fgure ) to determne the operatonal profles [4]. As a workng hypothess, we consder the entry of only one arcraft n the system (potental target) and use those numbers to each actvty accordng to fgure. The data related wth operaton of system s software modules (values estmated for falure rates by type of software modules and tmes of actvaton, e completon) were altered to serve for llustraton purposes. Step Determne operatonal profles (sequences of actvtes): profle (target entry nto the system, fght and destroy t) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( 4.) ( 4.4) ( 4.5) ( 5.) ( 5.2) ( 5.) ( 6.) ( 6.2) ( 6.) profle 2 (target already challenged but stll undamaged) ( 4.2) ( 4.) ( 4.4) ( 4.5) ( 5.) ( 5.2) ( 5.) ( 6.) ( 6.2) ( 6.) profle (target already challenged, stll undamaged and emerged from the ntal radar survellance sector) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( 4.4) ( 4.5) ( 5.) ( 5.2) ( 5.) ( 6.) ( 6.2) ( 6.) Each C4IS actvty s done through a varable number of specfc sets of software applcatons (). In turn, each conssts of a varable number of ndependent software modules executed compettvely (Table 2), whose characterstcs are presented n Table. 46

7 Knowledge Dynamcs Table 2. Correspondence between C4IS actvtes, specfc sets of software applcatons and number of software modules C4IS Specfc sets of software Number of software actvtes applcatons () modules Step 2 We calculate for each the average falure rate and the relablty durng operaton. We present detaled calculatons for. and 2., followng that for others to menton only the fnal results. The average falure rate for s calculated usng the equaton: m λ = λ, = where m = number of compettve actve software modules correspondng to 5. = m λ λ = ( ) 0 = 0, 000 hours - = 5 2. = m λ λ = ( ) 0 = 0, hours - = elablty functon wll be:. 2. = e = e λ λ. 0,000 = e = 2. 0,00045 = e = 0, ,99955 Table 4 presents values of average falure rates and relablty of specfc applcaton software sets. 47

8 Knowledge Dynamcs Table. Characterstcs of software modules sequentally actve / Types of software modules Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 ) Actvaton tme Completon tme Falure rate (x0-5 )

9 Knowledge Dynamcs 6. / Types of software modules Actvaton tme Completon tme Falure rate (x0-5 ) Table 4. Values of average falure rates and relablty of specfc applcaton software sets λ. 0,000 0, , , , , ,0009 0, ,0008 0, , , , , ,0006 0, , , ,0005 0, , , , , ,0004 0, ,0009 0, , , , , ,0004 0, ,0004 0, , , ,0004 0,99966 Step We calculate the relablty of C4IS actvtes = ϕ = ( ). = 0, = = = 0,99865 = 0,99806 = = = = 0,99865 = 0,99878 = 0,99785 Step 4 The relablty of operatonal profles pk s: 49

10 Knowledge Dynamcs = = = = = ,99529 = = ,999 0,99625 Consder the followng values for the operatonal profles probablty of occurrence p p p 2 = 0,75 = 0,5 = 0,0 p k : Step 5 MSTS relablty s: MSTS MSTS = N P = pk k = pk k = k = k = p + p p ( 0,75 0,99625) + ( 0,5 0,99529) + ( 0,0 0,999) = 0, If usng formula () for MSTS system s relablty calculaton, we can rewrte step 5, as follows: Step 5 () MSTS relablty s: MSTS N P = k = k = k = Also, there s a new step: k = 2 = 0, Step 6 We calculate the weghts assocated wth each usng the formula: = ln * / ln MSTS We present detaled calculatons for. and 2. assocated weghts, followng that for others to menton only the fnal results. Table 5 present values of weghts assocated to each specfc applcaton software set. ( 0,99969) / ln( 0,978994) 0, 0650 = ln / ln.. MSTS = ln = = ln / ln MSTS = ln 0,99955 / ln 0, = = ln / ln MSTS = ln 0,99958 / ln 0, = ( ) ( ) 0, 0500 ( ) ( ) 0, Table 5. The values of weghts assocated wth applcaton software sets.. 0, , , , , ,

11 Knowledge Dynamcs 2. 0,9998 0, , , , , , , ,9999 0, , , , , , , ,9990 0, , , ,9998 0, , , , , , , , , ,9995 0, , , ( Π ) ( Π 6. We execute the decreasng orderng of the weghts result strng. = Π ϕ ) , The concluson offered by the decreasng orderng of ths strng s that 4. and. have the largest weght (nfluence) on the relablty of the whole, any redesgn of the software modules that compose 4. and. beng hghly recommended n the relablty ncreasng process. eferences. Ghta, A. and Ionescu, V. Metode de calcul în fabltate, Mltary Techncal Academy Publshng House, Bucharest, Musa, J.D. Operatonal Profles n Software elablty Engneerng, IEEE Software Magazne, March, 99. Vaslescu, C. and Ghta, A. Contrbutons to the feld of C4IS Systems elablty Modelng, Proceedngs of the XXXIst Annual Scentfc Communcatons Sesson wth nternatonal attendance, Mltary Techncal Academy, Bucharest, -4 November Vaslescu, C. Prezentare generală a sstemelor de comandă ş control, Natonal Scentfc Communcatons Sesson, Ar Force Academy, Brasov, November Vaslescu, C. Probleme actuale în fabltatea sstemelor de comanda s control dn Fortele Aerene, Edtura Unverstat Translvana dn Brasov, 2009, pp * * * DoD Archtecture Framework verson.0 Deskbook, DoD Archtecture Workng Group, August * * * System and Software elablty Assurance Notebook, produced for ome Laboratory, New York, 997 5

12 Knowledge Dynamcs Codfcaton of references: [] [2] [] [4] [5] [6] [7] Ghta, A. and Ionescu, V. Metode de calcul în fabltate, Mltary Techncal Academy Publshng House, Bucharest, 996 Musa, J.D. Operatonal Profles n Software elablty Engneerng, IEEE Software Magazne, March, 99 Vaslescu, C. Prezentare generală a sstemelor de comandă ş control, Natonal Scentfc Communcatons Sesson, Ar Force Academy, Brasov, November 2000 Vaslescu, C. and Ghta, A. Contrbutons to the feld of C4IS Systems elablty Modelng, Proceedngs of the XXXIst Annual Scentfc Communcatons Sesson wth nternatonal attendance, Mltary Techncal Academy, Bucharest, -4 November 2005 * * * DoD Archtecture Framework verson.0 Deskbook, DoD Archtecture Workng Group, August 200 * * * System and Software elablty Assurance Notebook, produced for ome Laboratory, New York, 997 Vaslescu, C. Probleme actuale în fabltatea sstemelor de comanda s control dn Fortele Aerene, Edtura Unverstat Translvana dn Brasov, 2009, pp