Utjecaj faktora asimetrije i deformacije na kriterij optimizacije relativne brzine toka bimetalne trake St3S+0H13J

The design of new technologies of rolling bimetal plates poses a lot of problems with obtaining a uniform distribution of rolling reduction into the layers and a straight strip at the roll gap exit. This is the main cause to determine optimization criterion of relative flow rate. Computer analyses of the asymmetrical rolling process were performed in this study to optimize the conditions of production of bimetallic plates. A Finite Element Method-based program, Forge 2D, was used for computer simulation.Projektiranje novih tehnologija valjanja bimetalnih limova predstavlja mnogo problema glede ujednačene redukcije u slojevima ravne trake na izlazu između valjaka. Glavni razlog je određeni kriterij optimizacije relativne brzine protoka. U svrhu optimizacije uvjeta proizvodnje bimetalnih limova provedene su računske analize asimetričnog procesa valjanja. Za kompjutersku simulaciju se koristio program Forge 2D zasnovan na metodi konačnih elemenata

Utjecaj faktora asimetrije i deformacije na kriterij optimizacije relativne brzine toka bimetalne trake St3S+0H13J

The design of new technologies of rolling bimetal plates poses a lot of problems with obtaining a uniform distribution of rolling reduction into the layers and a straight strip at the roll gap exit. This is the main cause to determine optimization criterion of relative flow rate. Computer analyses of the asymmetrical rolling process were performed in this study to optimize the conditions of production of bimetallic plates. A Finite Element Method-based program, Forge 2D, was used for computer simulation.Projektiranje novih tehnologija valjanja bimetalnih limova predstavlja mnogo problema glede ujednačene redukcije u slojevima ravne trake na izlazu između valjaka. Glavni razlog je određeni kriterij optimizacije relativne brzine protoka. U svrhu optimizacije uvjeta proizvodnje bimetalnih limova provedene su računske analize asimetričnog procesa valjanja. Za kompjutersku simulaciju se koristio program Forge 2D zasnovan na metodi konačnih elemenata

Bimetalni lim St3S+Cu

The paper presents a theoretical analysis of the asymmetrical process of rolling bimetal plates composed of the base St3S layer and a Cu cladding layer. Investigation carried out aimed at determining the curvature of bimetal band depending on the value of roll peripheral speed asymmetry factor av. Computer simulations were performed on three different layer thickness ratios, HS/HH. Numerical studies were based on computer simulations carried out using the Forge 2D software. For computations, this program uses the finite-element method. The asymmetry of the process resulted from a non-uniform distribution of rolling reduction into the bimetal band layers, which caused the band to bend at the rolling mill exit. To counteract this behaviour, an asymmetry of working roll peripheral speeds was introduced.Članak daje teorijsku analizu učinka odnosa debljine sloja bimetalnih limova sastavljenih od osnovnog sloja St3S i sloja presvučenog bakrom. Provedena istraživanja su imala za cilj odrediti zakrivljenost bimetalne trake ovisno o vrijednosti faktora asimetrije av periferne brzine. Izvedene su kompjuterske simulacije tri sloja s različitim omjerima HS/HH debljine. Numeričke studije su se zasnivale na kompjuterskim simulacijama provedenim pomoću softvera Forge 2D. Za izračune, ovaj se program služi metodom konačnih elemenata. Asimetrija procesa rezultira od nejednolikog rasporeda redukcije u slojeve bimetalne trake koje uzrokuju savijanje trake na izlazu iz valjačkog stana. Kao protuteža takvom ponašanju uvedena je asimetrija perifernih brzina radnog valjka

Predviđanje zakrivljenosti bimetalne limene ploče Al-Cu tijekom asimetričnog hladnog valjanja

In the paper, solving a problem of rolling Al-Cu plates by the numerical way is presented. In the development of new technologies in rolling of bimetallic plates there are many problems both with ensuring a uniform strain distribution and producing a straight plate as well. Such a solution within research of the numerical simulation was obtained at the Forge 2 program based on finite element method. The cold rolling process was carried out at the temperature of 20 °C for 10 %, 20 % and 25 % relative rolling reduction. The curvature of bimetallic plate was numerically controlled by changing the speed of one roll. In this article the numerical analysis of asymmetrical rolling processes of plate composed with two metal layers, Al and Cu, has been done. At the work an influence of rotary speed ratio and value deformation on change of curvature bimetallic plate is determined.U radu je predstavljen numerički način rješavanja valjanja Al-Cu limenih ploča. U razvoju novih tehnologija za valjanje bimetalnih ploča ima mnogo problema i u osiguravanju jednolikog rasporeda deformacije i u proizvodnji ravnih ploča. U okviru provedenih istraživanja programa Forge 2, baziranom na metodi konačnih elemenata, ostvarena je numerička simulacija. Proces hladnog valjanja proveden je na temperaturi od 20 °C s relativnom redukcijom valjanja od 10 %, 20 % i 25 %. Zakrivljenost bimetalne ploče kontrolirala se numeričkim mijenjanjem brzine valjaka. U ovom članku napravljena je numerička analiza procesa asimetričnog valjanja ploče sastavljene od dva metal nasloja: Al i Cu. Također je utvrđen utjecaj omjera brzine rotacije i vrijednosti deformacije na promjenu zakrivljenosti metalne ploče

Research and investigative analysis using Kron's method of analyzing redundant structures

Response characteristics, frequency, and mode shape of Saturn SA-DI vehicle - analysis of redundant structure

Analitičko i numeričko utvrđivanje prostiranja temperature na traci hlađenoj zrakom

The paper analyzes the distribution of temperature of 60S2A steel strip cooled in air. Both analytical and numerical methods were applied in investigation. From among the known analytical methods of temperature distribution determination, Tselikov’s [1], and the Fourier’s [2] methods were used. The numerical examination of temperature distribution presented in the paper involved carrying out a computer simulation of strip air cooling. For this purpose, the Forge 2D software [3] was employed, which relies on the finite-element method in performing computations. Comparison of results obtained by analytical methods with numerical computation results and for the real technological process has also been made within the study.U radu se analizira prostiranje temperature u čeličnoj traci 60S2A hlađenoj zrakom. Tijekom istraživanja primjenjivala se i jedna i druga metoda. Između poznatih analitičkih metoda utvrđivanja prostiranja temperature koristile su se Tselikova [1] i Fourierova [2] metoda. Numeričko ispitivanje temperature koje je prikazano u radu uključuje i provođenje kompjuterske simulacije hlađenja trake zrakom. U tu je svrhu primijenjen Forgeov software 2D [3] koji se u računanju oslanja na metodu konačnih elemenata. Unutar studije je također provedena i usporedba rezultata dobivenih analitičkim metodama s numeričkim izračunima

Examination of the cut-off scores determined by the Ages and Stages Questionnaire in a population-based sample of 6 month-old Norwegian infants

<p>Abstract</p> <p>Background</p> <p>Few population-based samples have previously published performance on the Ages and Stages Questionnaire (ASQ), a recommended screening tool to detect infant developmental delay. The aim of the study was to investigate performance on the ASQ in a population-based sample of 6-month-old infants.</p> <p>Methods</p> <p>In this population-based questionnaire study from Oslo, Norway, the 30 item ASQ 6 month Questionnaire (N = 1053) were included, however without the pictograms, and compared to the Norwegian reference sample (N.ref) (N = 169) and to US cut-off values. Exclusion criteria were maternal non-Scandinavian ethnicity, infant age < 5.0 or > 7.0 months (corrected age), twins, and birth weight < 2.5 kg. Cut-off = 2.5 percentile (equivalent to mean minus 2 standard deviations). Pearson's Chi square and Mann-Whitney U were used to compare items and areas, respectively, with N.ref.</p> <p>Results</p> <p>The reported ASQ scores were lower on all but one of the 10 significantly different items, and in all areas except Personal social, compared to the N.ref sample. The estimated cut-off values for suspected developmental delay (Communication 25, Gross motor 15, Fine motor 18, Problem solving 25 and Personal social 20) were lower than the recommended American (US) values in all areas, and lower than the Norwegian values in two areas. Scores indicating need for further assessment were reached by 13.8% or 20.5% of the infants (missing items scored according to the US or the Norwegian manual), and by 33.8% or 30.3% of the infants using the recommended US or the Norwegian cut-off values, in this population-based sample. The Fine motor area demonstrated a large variability depending on the different cut-off and scoring possibilities. Both among the items excluding pictograms and the items that do not have pictograms, approximately every third item differed significantly compared to the N.ref sample.</p> <p>Conclusion</p> <p>The psychomotor developmental scores were lower than in the reference samples in this study of ASQ 6 month Questionnaire; to our knowledge the first study to be both representative and comparatively large. Approximately every third child with birth weight above 2.5 kg, received scores suggesting further assessment using recommended ASQ cut-off scores.</p

Maternal mental health predicts risk of developmental problems at 3 years of age: follow up of a community based trial

<p>Abstract</p> <p>Background</p> <p>Undetected and untreated developmental problems can have a significant economic and social impact on society. Intervention to ameliorate potential developmental problems requires early identification of children at risk of future learning and behaviour difficulties. The objective of this study was to estimate the prevalence of risk for developmental problems among preschool children born to medically low risk women and identify factors that influence outcomes.</p> <p>Methods</p> <p>Mothers who had participated in a prenatal trial were followed up three years post partum to answer a telephone questionnaire. Questions were related to child health and development, child care, medical care, mother's lifestyle, well-being, and parenting style. The main outcome measure was risk for developmental problems using the Parents' Evaluation of Developmental Status (PEDS).</p> <p>Results</p> <p>Of 791 children, 11% were screened by the PEDS to be at high risk for developmental problems at age three. Of these, 43% had previously been referred for assessment. Children most likely to have been referred were those born preterm. Risk factors for delay included: male gender, history of ear infections, a low income environment, and a mother with poor emotional health and a history of abuse. A child with these risk factors was predicted to have a 53% chance of screening at high risk for developmental problems. This predicted probability was reduced to 19% if the child had a mother with good emotional health and no history of abuse.</p> <p>Conclusion</p> <p>Over 10% of children were identified as high risk for developmental problems by the screening, and more than half of those had not received a specialist referral. Risk factors for problems included prenatal and perinatal maternal and child factors. Assessment of maternal health and effective screening of child development may increase detection of children at high risk who would benefit from early intervention.</p> <p>Trial registration</p> <p>Current Controlled Trials ISRCTN64070727</p