Time delay in thin slabs with self-focusing Kerr-type nonlinearity

Time delays for an intense transverse electric (TE) wave propagating through a Kerr-type nonlinear slab are investigated. The relation between the bidirectional group delay and the dwell time is derived and it is shown that the difference between them can be separated into three terms. The first one is the familiar self interference time, due to the dispersion of the medium surrounding the slab. The other two terms are caused by the nonlinearity and oblique incidence of the TE wave. It is shown that the electric field distribution along the slab may be expressed in terms of Jacobi elliptic functions while the phase difference introduced by the slab is given in terms of incomplete elliptic integrals. The expressions for the field intensity dependent complex reflection and transmission coefficients are derived and the multivalued oscillatory behavior of the delay times for the case of a thin slab is demonstrated

Laboratory evolution of host plant utilization in the bean weevil (Acanthoscelides obtectus)

International audienc

Manufacturing Cycle Time Analysis and Scheduling to Optimize Its Duration

This paper reports the results of investigations on manufacturing cycle times for special-purpose products. The company performs serial production characterized by complex and diverse technologies, alternative solutions and combined modes of workpiece movement in the manufacturing process. Because of various approaches to this problem, an analysis of previous investigations has been carried out, and a theoretical base is provided for the technological cycle and factors affecting the manufacturing cycle time. The technological and production documentation of the company has been analysed to establish the technological and real manufacturing cycle times, total losses and flow coefficients. This paper describes the original approach to production cycle scheduling on the grounds of investigations of manufacturing capacity utilization levels and causes of loss, in order to measure their effects and to reduce the flow coefficient to an optimum level. The results are a segment of complex studies on the production cycle management of complex products, accomplished in the company in the period from 2010 to 2012

Manufacturing Cycle Time Analysis and Scheduling to Optimize Its Duration

This paper reports the results of investigations on manufacturing cycle times for special-purpose products. The company performs serial production characterized by complex and diverse technologies, alternative solutions and combined modes of workpiece movement in the manufacturing process. Because of various approaches to this problem, an analysis of previous investigations has been carried out, and a theoretical base is provided for the technological cycle and factors affecting the manufacturing cycle time. The technological and production documentation of the company has been analysed to establish the technological and real manufacturing cycle times, total losses and flow coefficients. This paper describes the original approach to production cycle scheduling on the grounds of investigations of manufacturing capacity utilization levels and causes of loss, in order to measure their effects and to reduce the flow coefficient to an optimum level. The results are a segment of complex studies on the production cycle management of complex products, accomplished in the company in the period from 2010 to 2012

Planiranje i projektovanje velikih elektroenergetskih sistema i njihov uticaj na životnu sredinu

This paper analyzes the impact of planning and designing large power systems on the environment, such as the DSP 400 kV optical cable from the Montenegrin coast to Pljevlja. It is a very complex and multidisciplinary project, and involves the analysis of a number of important factors and cause-effect relationships that such a system can produce. The analysis was guided by the fact that this is an atypical example, from the planned and implemented aspect unknown both on the national and wider regional level. For this reason, it is challenging to shed light on the consequences of any such system and structure, which is specific in many ways, and whose repercussions in the near future are still vague. The paper discussed European and international experiences as well as their perceptions of problems with similar solutions in practice.U radu se analizira uticaj planiranja i projektovanja velikih elektroenergetskih sistema na životnu sredinu, kao što je Detaljni prostorni plan (DPP) postavljanja 400 kV optičkog kabla od Crnogorskog primorja do Pljevalja. To predstavlja vrlo kompleksan i multidisciplinaran posao i podrazumeva analizu niza bitnih faktora, kao i uzročnoposledičnih veza koje jedan takav sistem može proizvesti. U analizi se rukovodilo činjenicom da se radi o atipičnom primeru, s planerskog i izvedbenog aspekta nepoznatog na nacionalnom, ali i širem regionalnom nivou. Zbog toga je bilo potrebno rasvetliti posledice jednog ovakog sistema i konstrukcije, koji je specifičan po mnogo čemu, i čije se reperkusije u bližoj budućnosti tek mogu nazreti. U istraživanju su razmatrana evropska i svetska iskustva, i njihova percepcija posmatranja problema sa sličnim rešenjima u praksi

Improvements of the production resources planning process under conditions of uncertainty

Научни циљ докторске дисертације је унапређење процеса управљања производним ресурсума у условима неизвесности применом модификованих модела оптимизације. У раду се интегришу постојећи модели, методе и технике савремене производње у условима ризика, при чему се пројектују решења која су осетљива на промену услова пословања. У докторској дисертацији су обрађене бројне методе и технике које се примењују у оптимизацији произвдних ресураса. Посебан значај је у имплементацији методе ФЛП (фази линерног програмирања) и ФАХП (фази аналитичко хијерархиског процеса) за процену параметара циљне функције при оптимизацији. Добијени резултати исраживања омогућавају рационално планирање производних ресурса у условима неизвесности, како би се обезбедило оптимално управљање предузећем. Идентификација узрочно-последичне везе између вредности критеријума и алтернатива, омогућила је пројектовање модела за оптимално управљање предузећем. Предложена је шема методолошких корака анализе производних ресурса у којима је присутна неизвеснот, кључна за оптимизацију процеса планирања. Основни ресурси у процесу производње који су истражени су: неизвесност потражње за производима, неизвесност у погледу машинских капацитета и неизвесност у погледу расположивих кадровских ресурса. Набавка материјала је анализирана као стохастичка функција и за одређене репроматеријале генерисана je функција расподеле вероватноћа. Важан допринос је укључивљње неизвесности у процес планирања производних капацитета, применом фази линеарног програмирања. Спроведена је упоредна анализа класичног линеарног програмирања и фази линеарног програмирања у циљу добијања максималног профита и минималних трошкова. Пројектовани план производње у условима неизвесности указује на реализацију већег профита ако се примене преложена решења.Scientific goal of the doctoral dissertation is to improve the production resources management process under uncertainty by applying modified optimization models. The paper integrates the existing models, methods and techniques of modern-day production under conditions of risk, while designing solutions that are sensitive to a change in business environment. In the doctoral dissertation are discussed numerous methods and techniques used in the production resources optimization. The implementation of FLP (Fuzzy linear programming) and FAHP (Fuzzy analytic hierarchy process) methods for estimation of target function parameters in the optimization is of particular importance. The obtained research results provide rational planning of production resources under conditions of uncertainty in order to ensure optimal management of the company. The identification of the cause-and-effect relationship between the values of the criteria and the alternatives allowed the designing of a model for optimal management of the company. An outline of methodological steps is proposed for the analysis of production resources where uncertainty is present, which is crucial for the planning process optimization. The basic resources in the production process that have been explored are: product demand uncertainty, uncertainty in terms of machine capacity, and uncertainty in terms of available human resources. Material procurement was analyzed as a stochastic function and a probability distribution function was generated for certain raw materials. An important contribution is the inclusion of uncertainty in the production capacity planning process using the fuzzy linear programming. A comparative analysis of classical linear programming and fuzzy linear programming was performed for the purpose of obtaining the maximum profit and the minimum costs. The designed plan of production under conditions of uncertainty indicates the realization of higher profits if the proposed solutions are applied

Influence of the composition and temperature of water on the choice of the heat scheme and materials for the equipment for geothermal energy utilization

U disеrtаciјi su prikаzаni rеzultаti istrаživаnја uticаја sаstаvа i tеmpеrаturе gеоtеrmаlnе vоdе nа izbоr tоplоtnе šеmе i mаtеriјаlа оprеmе zа kоrišćеnје gеоtеrmаlnе еnеrgiје. Rеzultаti istrаživаnја оmоgućаvајu dа sе u zаvisnоsti оd izdаšnоsti izvоrа gеоtеrmаlnе vоdе, lјеnоg sаstаvа i tеmpеrаturе izvrši: 1. Аnаlizа mоgućnоsti primеnе gеоtеrmаlnе еnеrgiје zа pоtrеbе grеjаnја; 2. Uzоrkоvаnје gеоtеrmаlnih vоdа i оdrеđivаnје nјеnih svојstаvа; Z. Izbоr tоplоtnе šеmе i mаtеriјаlа zа izrаdu еlеmеnаtа grејnоg sistеmа (cеvоvоdi, аrmаturа, izmеnјivаč tоplоtе) zа kоrišćеnје gеоtеrmаlnе еnеrgiје; 4. Utvrđivаnје pаrаmеtаrа pоtrеbnih zа pоstupаk dimеnziоnisаnја izmеnјivаčа tоplоtе. Nа оsnоvu еkspеrimеntаlnih istrаživаnја u lаbоrаtоriјskim i еksplоаtаciоnim uslоvimа, pоmоću оdgоvаrајućih mеrnih instаlаciја, utvrđеnо је kоrоziоnо pоnаšаnје mеtаlnih mаtеriјаlа (uglјеnični čеlik, nеrđајući čеlik i sivо livеnо gvоžđе), kао i prоmеnа оtpоrа prоvоđеlјu tоplоtе uslеd zаprlјаlја izmеnјivаčа tоplоtе sа gеоtеrmаlnоm vоdi iz bušоtinе PIK"7.јuli"-Dеbrc. Тоm prilikоm је kоnstаtоvаnо slеdеćе: • Zа uzоrkе оd uglјеničnоg čеlikа i livеnоg gvоžđа brzinа kоrоziје zаvisi оd brzinе prоticаnја gеоtеrmаlnе vоdе, pri čеmu је u stаnјu mirоvаnја vоdе brzinа kоrоziје vеоmа mаlа, а sа pоvеćаnјеm brzinе znаčајnо rаstе (pri brzinаmа vоdе оd 0,5+2 m/s pоvеćаnје је nеkоlikо dеsеtinа putа); • Zа uzоrkе оd nеrđајućih čеlikа niје ustаnоvlјеnа znаčајnа rаzlikа u brzini kоrоziје zа slučај mirоvаnја vоdе i zа slučај nјеnоg prоticаnја; • Nа оsnоvu ispitivаnја u еksplоаtаciоnim uslоvimа utvrđеnа је linеаrnа prоmеnе ukupnih оtpоrа prоvоđеnјu tоplоtе izmеnјivаčа tоplоtе sistеm cеv-u-cеv uslеd zаprlјаnја sа gеоtеrmаlnоm vоdоm iz bušоtinе PIK"7.јuli"- Dеbrc. Тоkоm ispitivаnја vrеdnоst kоеficiјеntа prоlаzа tоplоtе sе smаnјilа sа pоčеtnih 1100 [W/m2 .K] nа оkо 650 [W/m2•K], nа krајu ispitivаnја. Izvršеnе su dvе sеriје ispitivаnја оd kојih је svаkа trајаlа оkо 90 dаnа.The Ph.D. dissertation presents the results of an investigation of the influence of the composition and temperature of geothermal water on the choice of the heat scheme and materials for the equipment for geotherma energy utilization. Depending on the specific yield of geothermal springs, its composition and temperature, the results of theoretical and experimental investigations enaЬle the following: 1. An analysis of the potentials for utilization of geothermal water for heating; 2. Sampling of geothermal water and determination of its properties; З. The choice of materials for manufacturing the components of the system for geothermal energy utilization; 4. Determination of the parameters required for the design of heat exchangers. On the basis of experimental investigations carried out Ьу using the appropriate measuring equipment, it was possiЬle to determine the corrosion of meterials (carbon steeel, stainless steel and cast iron) and а change in overal fouling resistance caused Ьу geothermal water from the borehole of PIK "7 .juli"-Debrc. In this connection, it was determined as follows: • in the case of carbon steel and cast iron samples, the corrosion rate depends on the flow rate of geothermal water, wereby the corrosion rate in case of stationary water is very small; the corrosion rate increases significantly as the water flow rate of water increases (at the flow rates of water from 0,5 to 2 rn!s, it increases several times ); • in the case of stainless steel samples, no significiant difference in the corrosion rate was observed in the case of stationary water, as well as in the case og water flow; • during the 90-day investigation, а linear dependence of overal fouling resistance in time was determined. The overal heat transfer coefficient of testing heat exchanger declined from 1100 (W/m2K) at the beginning of the investigation to 650 (W/m2K) at its end

Textural characteristics of fermented milk beverages produced by kombucha

Rheological properties of fermented dairy products are very important parameters of the product quality. The behaviour of gel formed during fermentation of milk is influenced by a great number of factors, such as: milk composition, starter culture, flavourings addition, etc. The aim of this research was to examine the influence of fat content, and kombucha inoculum concentration on textural characteristics of fermented milk beverages: firmness, consistency, cohesiveness and viscosity index after production and during 10 days of storage. Higher fat content of beverage affects the firmness, consistency, cohesiveness and viscosity index, while higher amount of inoculum in beverages has an opposite effect on textural characteristics of samples during storage

The programme for professional development of chemistry teachers’ assessment competency

The aim of this paper is to investigate the effects of the programme for professional development of chemistry teachers on their competencies for conducting formative and summative assessment in chemistry teaching. The programme participants were 30 chemistry teachers from primary and secondary schools. Data were collected using a questionnaire at the beginning and at the end of the programme implementation. The programme included four workshops with the same structure: the introduction, group work and the discussion of the results obtained through group work. The workshops focused on: i) the assessment as a support for chemistry learning; ii) the harmonization of teaching and learning activities, formative and summative assessment, feedback from formative assessment and the criteria used to evaluate students in summative assessment; iii) the evaluation of the validity of tasks used for formative and summative assessment according to the curricula aims and the educational standards; iv) designing tasks for monitoring students’ progress towards certain educational standards. Teachers’ responses show the impact of the programme for the development of their competencies for assessment, particularly regarding formative and summative assessment and designing various kinds of assessment in accordance with the achievement standards