Utjecaj direktnih pogona na strukturu pogonskih mehanizama

Napredak tehnologije, s primjenom u gradnji pogonskih motora i sustava upravljanja, omogućava danas velike promjene u oblikovanju pogonskih mehanizama tehničkih sustava. Neposredno povezivanje pogonskog motora i radnog člana mehanizma, bez mehaničkog prijenosnika kao posrednika, stoljetni je san vizionara u strojarstvu. U radu su istražene moguće izvedbe direktnih pogona i njihov utjecaj na opći oblik pogonskih mehanizama tehničkih sustava. Predloženim oblikovanjem visokomomentnog motora željela se pronaći univerzalna izvedba sa širim spektrom primjene u pogonskim mehanizmima. Provedena su istraživanja troškova u razvoju direktnih pogona, te su predložene smjernice za sniženja tih troškova. Raščlambom strukture direktnog pogona postavljeni su principi oblikovanja pojedinih parcijalnih funkcija i definiran njihov utjecaj na sustav pogonskog mehanizma. Sintezom tehničke funkcije, strukture i veze s okolinom utvrđena je metoda preciznog definiranja pogona za određene namjene u tehničkim sustavima. Pored istraženih i predloženih struktura pogonskih mehanizama s direktnim pogonom, u okviru rada je razvijen direktni pogon eksperimentalnog vozila, ugrađen u pogonski kotač standardnih dimenzija. Na direktnom pogonu eksperimentalnog vozila provedeni su eksperimenti s kontrolnim mjerenjima, a dobiveni rezultati potvrdili su njegovu primjenjivost i brojne visoke pogonske performanse (visoki moment vrtnje u širokom rasponu brzina, brzi odziv, zadovoljavajuću valovitost momenta vrtnje) takvih pogona u odnosu na klasične pogonske sustave. Istraživanjem značajki novog pogonskog sustava s direktnim pogonom postavljeni su kriteriji, mjerila i pravila oblikovanja tog sustava, čime je stvorena i neophodna baza znanja za kreiranje tog sustava

Metodologija izračuna otpora u zavoju vlaka u ovisnosti od mase i brzine

A methodology for determining curving resistances of track vehicles is proposed. The methodology is aimed to gain insight into influence of the arrangement of masses along the train and the train speed on the curving resistance based on test results conducted by using a scaled down train. The utilized scaled down train is a HO scale line freight train in ratio of 1:87 consisting of a EMD SD 35 locomotive and FALNS 121 freight wagons. The considered variants of the train arrangements are as follows: empty train (PPPPPP), one loaded wagon in the front/in the end (TPPPPP and PPPPPT) and two loaded wagons in the front/in the end (TTPPPP and PPPPTT). The total train curving resistance WR is determined based on the decrease of the train steady-state curving speed vR when compared to the train steady-state speed on the straight track v∞ under same operating conditions. The curving resistance of a train of arbitrary arrangement is calculated as the difference between the train driving force when driving on a straight, horizontal track FV (constant resistance WS) and the total resistance when curving WU (driving force FV in curve). The constant resistances of the locomotive and empty and loaded wagons are determined by application of the gravitational method.Metodologija izračuna otpora u zavoju tračničkih vozila osmišljena je za izvođenje eksperimenta na umanjenom modelu teretnog vlaka u HO standardu 1:87, lokomotiva EMD SD 35 i vagoni FALNS 121. Formirani model služi za istraživanje utjecaja vrijednosti i rasporeda mase tereta unutar sastava voza, te brzine gibanja na vrijednost otpora u zavoju. Gravitacijskom metodom se određuju stalni otpori (otpori u ravnini) lokomotive, praznog i natovarenog vagona. Razmatrane kombinacije sastava vlaka su: prazan vlak (PPPPPP), jedan natovaren vagon napred nazad (TPPPPP i PPPPPT) i dva natovarena vagona napred nazad (TTPPPP i PPPPTT). Otpor u zavoju cijelog vlaka WR dobije se na osnovu smanjenja brzine gibanja vlaka u zavoju vR prema brzini gibanja vlaka na pravcu v∞ pri istim referentnim uvjetima. Otpor u zavoju WR izračunava se kao razlika vučne sile vlaka na pravcu FV (stalnog otpora WS) i ukupnog otpora cijelog vlaka WU (vučna sila FV u zavoju) pri gibanju u zavoju za svaku odabranu kombinaciju sastava vlaka

Projektiranje sustava regulacije vertikalne sile tribometra s uzorkom na disku uključujući aktivno i pasivno prigušenje vertikalnih vibracija

This paper presents the design of a computer-controlled pin-on-disk tribometer for friction characterization of various friction sliding pairs. The tribometer setup comprises two high-bandwidth servomotors for the control of the rotating disk and the normal load-related spindle drive, as well as a high-precision tri-axial piezoelectric force sensor for normal and tangential forces measurement. Since the spindle drive system is characterized by notable compliance effects, the normal force cascade control system is designed with the aim of vertical vibrations active damping. In order to compensate for the unevenness of the rotating disk surface and associated high-level perturbations in the specimen normal force, the normal force control system is extended with a feedforward compensator of the disk unevenness disturbance, and a dedicated leaf spring suspension system is designed. The effectiveness of the proposed system of vertical vibrations damping is verified experimentally.U članku je prikazan dizajn računalom upravljanog tribometra s uzorkom na disku za karakterizaciju različitih kliznih parova. Postav tribometra sadrži dva električna servomotora visokih dinamičkih performansi koji se koriste za regulaciju rotacijskog diska i navojnog vretena za generiranje normalne sile, te tro-osni piezoelektrični senzor za mjerenje normalne i tangencijalne sile. Kako je pogon navojnog vretena karakteriziran značajnom elastičnošću, kaskadni sustav regulacije sile je projektiran s ciljem aktivnog prigušenja vertikalnih vibracija. U svrhu kompenzacije značajnih neravnina površine rotacijskog diska i s njima povezanih velikih amplituda perturbacija normalne sile na uzorak, sustav regulacije normalne sile proširuje se unaprijednim kompenzatorom poremećaja uslijed neravnina površine diska, te za tu svrhu namijenjenim sustavom ovjesa s lisnatim oprugama. Učinkovitost predloženog sustava za prigušenje vertikalnih vibracija provjerena je eksperimentalnim putem

The golden ratio in probablistic and artificial intelligence

Problem linijskog odsječka utemeljenog na omjeru zlatnog reza φ = 1,618033 ima analogiju u vjerojatnosti. Rješenje elementarne eksponencijalne raspodjele, posebice ističe vrijednost 2lnφ. Ova vrijednost također ima ključnu ulogu u odnosu Rikatijevih hiperboličnih funkcija s Fibonačijevim i Lukasovim brojevima u kontinuiranom području. Time se uspostavlja bliska veza između konstanti e i φ. Izvedena su dva nova teorema o konvergenciji konstanti φ i e . Broj e je temelj Markovskih procesa, koji su našli primjenu u teoriji vjerojatnosni i umjetne inteligencije. Omjer konstanti e i φ, kao i mnogi drugi prirodni fenomeni na temelju zlatnog reza, ističu potrebu za proširenjem područja vjerojatnosni i umjetne inteligencije.The problem of the line section based on the golden ratio φ = 1,618033 has the analogy in probability. The solution of the elementary exponential distribution relies on the value 2lnφ in particular. This value also plays a key role to Riccati hyperbolic functions with Fibonacci and Lucas numbers in continuous domain. This establishes a close relationship between the constants e and φ. Two new theorems on the convergence between the constants φ and e were derived. The number e is the foundation of Markov processes, which find applications in probabilistic and artificial intelligence theory. The ratio between the constants φ and e, as well as many other natural phenomena based on the golden ratio, highlight the need to expand the field of probabilistic and artificial intelligence

A Comparison of Welded Structure Cost Calculation Methods

With the increase in material and labour costs, the optimization of welded steel structures is gradually becoming a necessity. Precise cost calculation methods are a prerequisite for the optimization process; they enable the designers to differentiate between product variations and select the best one. However, while the calculation of the material cost is simple, the calculation of fabrication costs, which include the costs of cutting, handling, welding, and surface preparation, is harder to define. Thus, in this paper, two available cost calculation methods are compared by observing two specific welded structures: a welded I beam and a gearbox housing. Both the total and the partial costs were compared. Based on the results, it was concluded that the methods are in agreement considering the total cost values and that both methods can differentiate between the design variations comparably. On the other hand, partial costs of process segments differed, mostly due to variations in the pre-defined scope of each process (e.g., one method included handling in the material costs, while the other included it in the welding costs)

Mathematical identification of influential parameters on the elastic buckling of variable geometry plate

The problem of elastic stability of plates with square, rectangular, and circular holes as well as slotted holes was discussed. The existence of the hole reduces the deformation energy of the plate and it affects the redistribution of stress flow in comparison to a uniform plate which causes a change of the external operation of compressive forces. The distribution of compressive force is defined as the approximate model of plane state of stress. The significant parameters of elastic stability compared to the uniform plate, including the dominant role of the shape, size, and orientation of the hole were identified. Comparative analysis of the shape of the hole was carried out on the data from the literature, which are based on different approaches and methods. Qualitative and quantitative accordance of the results has been found out and it verifies exposed methodology as applicable in the study of the phenomenon of elastic stability. Sensitivity factor is defined that is proportional to the reciprocal value of the buckling coefficient and it is a measure of sensitivity of plate to the existence of the hole. Mechanism of loss of stability is interpreted through the absorption of the external operation, induced by the shape of the hole

Integrating enterprise project portfolio management with the balanced scorecard: a case from the pharmaceutical industry

Enetrprise Project Portfolio Management (EPPM) ima ključnu ulogu u poboljšanju uspješnosti upravljanja projektima tvrtke,.Unatoč njegovoj vrijednosti, EPPM je do sada bilo teško povezati sa modelima za mjerenje rezultata izvršenjem,kao što je npr. Balanced Scorecard (BSC). Stoga je glavni cilj ovog rada bio razviti jedinstven EPPM - BSC model, kako na starteškoj, tako i na projektnoj razini.Model je testiran na slučaju iz farmaceutske industrije, gdje se pokazao vrlo uspješnim.Za razliku od prijašnjih istraživanja,ovaj rad dokazuje kako BSC i EPPM mogu uspješno funkcionirati zajedno. Nadalje, njihova sinergija dovodi do kaskade ciljeva sa strateške na projektnu razinu te tako omogućuje projetknim menadžerima razvoj ključnih pokazatelja izvršenja, koji direktno ocrtavaju ispunjenje poslovne strategije.Ovaj rad je posebno koristan za tvrtke, koje su fazi razvoja vlastitog sustava upravljanja učinkom, jer ovaj članak pokazuje testiranje modela na primjeru stvarne farmaceutske kompanije. Ipak, potrebna su daljnja istraživanja, posebice u području odabira ključnih pokazatelje izvršenja unutar perspektiva BSC-a.Enterprise Project Portfolio Management systems (EPPM) play a critical role in obtaining organizational success and are far more than just IT projects. Despite their popularity, EPPMs have seemed to fail when trying to work together with performance management systems, e.g. the Balanced Scorecard (BSC). Therefore, the aim of this study was to develop an EPPM-BSC model at both the strategic and project level. We tested the model on a case from the pharmaceutical industry and found it to be successful. Contrary to past studies, these results show that BSC, when integrated with EPPM, can be successfully cascaded from the strategic level on to the project level and thus enable managers in developing their own project scorecards. This paper is especially useful to companies who are in pursuit of developing their own performance management systems. Still, further research is needed, especially in finding a suitable model for KPI selection

Metodologija izračuna otpora u zavoju vlaka u ovisnosti od mase i brzine

A methodology for determining curving resistances of track vehicles is proposed. The methodology is aimed to gain insight into influence of the arrangement of masses along the train and the train speed on the curving resistance based on test results conducted by using a scaled down train. The utilized scaled down train is a HO scale line freight train in ratio of 1:87 consisting of a EMD SD 35 locomotive and FALNS 121 freight wagons. The considered variants of the train arrangements are as follows: empty train (PPPPPP), one loaded wagon in the front/in the end (TPPPPP and PPPPPT) and two loaded wagons in the front/in the end (TTPPPP and PPPPTT). The total train curving resistance WR is determined based on the decrease of the train steady-state curving speed vR when compared to the train steady-state speed on the straight track v∞ under same operating conditions. The curving resistance of a train of arbitrary arrangement is calculated as the difference between the train driving force when driving on a straight, horizontal track FV (constant resistance WS) and the total resistance when curving WU (driving force FV in curve). The constant resistances of the locomotive and empty and loaded wagons are determined by application of the gravitational method.Metodologija izračuna otpora u zavoju tračničkih vozila osmišljena je za izvođenje eksperimenta na umanjenom modelu teretnog vlaka u HO standardu 1:87, lokomotiva EMD SD 35 i vagoni FALNS 121. Formirani model služi za istraživanje utjecaja vrijednosti i rasporeda mase tereta unutar sastava voza, te brzine gibanja na vrijednost otpora u zavoju. Gravitacijskom metodom se određuju stalni otpori (otpori u ravnini) lokomotive, praznog i natovarenog vagona. Razmatrane kombinacije sastava vlaka su: prazan vlak (PPPPPP), jedan natovaren vagon napred nazad (TPPPPP i PPPPPT) i dva natovarena vagona napred nazad (TTPPPP i PPPPTT). Otpor u zavoju cijelog vlaka WR dobije se na osnovu smanjenja brzine gibanja vlaka u zavoju vR prema brzini gibanja vlaka na pravcu v∞ pri istim referentnim uvjetima. Otpor u zavoju WR izračunava se kao razlika vučne sile vlaka na pravcu FV (stalnog otpora WS) i ukupnog otpora cijelog vlaka WU (vučna sila FV u zavoju) pri gibanju u zavoju za svaku odabranu kombinaciju sastava vlaka

Direct drive lifts

U radu se opisuju dizala s direktnim pogonom polazeći od činjenice da su kod njih pogonski mehanizmi zasebni tehnički sustavi unutar građevine. Prikazane su strukture pogonskih mehanizama kod kojih se zahtijeva: mali prostor, bešuman rad, programska upravljivost, uz veoma visoku pogonsku pouzdanost i sigurnost. Opisani su visokomomentni motori koji svojim visokim tehničkim karakteristikama omogućuju ispunjenje traženih zahtjeva. Istaknute su prednosti primjene opisanih sustava.Direct drive lifts are presented and an emphasis is placed on the fact that their driving mechanisms are separate technical systems within a facility/building. The authors present the structure of driving mechanisms which require a small amount of space, operate without any noise, can be programmed, and present a high level of operating reliability and safety. High torque engines, capable of fulfilling stringent requirements because of their advanced technical properties, are described. Advantages of the described systems are presented

Zlatni rez u vjerojatnosti i umjetnoj inteligenciji

Problem linijskog odsječka utemeljenog na omjeru zlatnog reza φ = 1,618033 ima analogiju u vjerojatnosti. Rješenje elementarne eksponencijalne raspodjele, posebice ističe vrijednost 2lnφ. Ova vrijednost također ima ključnu ulogu u odnosu Rikatijevih hiperboličnih funkcija s Fibonačijevim i Lukasovim brojevima u kontinuiranom području. Time se uspostavlja bliska veza između konstanti e i φ. Izvedena su dva nova teorema o konvergenciji konstanti φ i e . Broj e je temelj Markovskih procesa, koji su našli primjenu u teoriji vjerojatnosni i umjetne inteligencije. Omjer konstanti e i φ, kao i mnogi drugi prirodni fenomeni na temelju zlatnog reza, ističu potrebu za proširenjem područja vjerojatnosni i umjetne inteligencije