Overhead crane anti-swing system based on the Pontryagin’s maximum principle

Overhead cranes are widely used at industrial enterprises for transportation of materials and products. They are successfully adaptable to technological processes used at an enterprise and their exploitation is inexpensive; in addition, the price of cranes is relatively low. However, extension of requirements set for technological processes results in shortened time for transportation and stiffened requirements for accuracy of cargo delivery and cargo safety. In the attempts to satisfy the latter requirements, particular attention is paid to swings of the cargo-holding rope. There is a number of factors that cause increased requirements for the control system of the crane drive. The slewing movement affects the total system of the crane and aggravates the crane movement control. In modern overhead cranes, the abilities and qualification of an operator (who is assisted by a certain anti-swing system) predetermine the cargo swings and the accuracy of its positioning. The said circumstance latterly caused a particular attention to computerisation of overhead crane control. However, a nonlinearity of the mechanical system of a crane and complicated control of swings often cause undesirable swings, in particular in the beginning and the end of cargo transporting process, thus reducing the efficiency of usual crane control systems. In addition, it should be taken into account that the parameters of a crane, as a controlled mechanical system, depend on the cargo and the conditions of its transportation. Consequently, a development of an effective cargo swing reduction system is a currently topical engineering problem

Dynamic reaction forces of an overhead crane on lifting

In the recent period, girder bridge cranes are replaced with double-beam overhead cranes with a rectangular cross-section of the beams. In addition, new materials are used for producing them thus applying other values of allowable loads and deformations. The paper focuses on two overhead cranes working for JSC Vilniaus kranai (Vilnius Cranes). The presented mathematical model provides an opportunity to assess the structural peculiarities of the above introduced cranes. The calculated results of dynamic loads appearing in the beginning and the end of the lifting process and having an impact on the lifting mechanism and metal structure are provided in the article

Experimental study of carriageway operational condition influence on acoustic roadside area pollution

Environmental noise management is an important part of the policy across the EU policy context, because transportation noise is a significant local environmental problem for most of the urban population. Increasing numbers of vehicles are associated with growing noise levels from road transport in urban areas and rising public health problems. Motor transport is considered to be a main source of noise pollution, so it is important to investigate the level of traffic noise and assess the relationship with traffic flows. The paper describes the main methods for determination of noise characteristics of traffic flows. The dependences for the prediction of the equivalent noise level and the results of field measurements of sound levels are presented. The results of field experiments and the calculated values of sound levels obtained by the analytical method are tested for homogeneity, using the Wilcoxon test. Experimental studies have established that the external sound level depends largely on the speed of vehicles, road conditions, and basic operating characteristics of highways. The analytical method associated with the use of deterministic and probabilistic models makes it possible to predict the traffic noise. But when dealing with the foregoing methods, there arise specific problems, many of which have not been resolved: there is no uniform terminology, nor is there any consensus on the use of noise characteristics of traffic flows in calculations at different stages of construction and reconstruction of highways of a certain traffic flow model under conditions of human settlements. Standardized measurement methods have been established and revised throughout the years by many renowned researchers. These methodologies have been revised in order to minimize problems that may occur and may not be foreseen by a less experienced researcher when adopting the measurement methods. Standardizing the measurement method is also useful for researchers because it becomes possible for researchers from around the world to compare their data. The joint effect of road conditions and the operational status of the roadway on the acoustic pollution of the roadside area is not fully taken into account. Therefore, applying the internationally recognized acoustical measurement standards is a good way to start any noise measurement experiment. The purpose of experimental research is to investigate the joint effect of road conditions and the operational status of the roadway on the acoustic pollution of the roadside area of settlements: identify the main characteristics of noise produced by traffic flows, consider the comparability of results of the field experiment and analytical computations. Slopes of 20…40‰ have little impact on the noise caused by the movement of passenger cars and trucks. In this case, the average acoustic emissions are identical to those used in the prediction of noise mode

Numerical Simulation of a Pulsating Flow Generated in an Ejector

This paper presents a numerical simulation of a pulsating flow generated inside an ejector; the flow is intended to oxidize ferrous iron (Fe2+) dissolved in drinking water to ferric iron (Fe3+). The pulsating flow ejector can be used in water treatment systems where the water is saturated with oxygen before being treated by filters. It is shown that the pulsating flow is generated due to fluctuations in the pressure, density, and velocity of the flow inside the ejector. It is established that the flow pressure inside the ejector varies from 0.513 to 0.0719 MPa, the flow density varies from 4.64 to 0.66 kg/m3, and the flow velocity varies from 0 to 590 m/s. Numerical simulation results have shown that an acoustic field is generated inside the ejector during the mixing of air with water, which accelerates the coagulation of iron particles. The obtained sound power level value of 100 dB shows that the pulsating flow ejector can be used for non-reagent water treatment

An Investigation Into Fault Diagnosis in a Rotor-Bearing System with Dampers Used in Centrifugal Milk Separators

This paper deals with the problems encountered in the fault diagnosis in damped rotor-bearing systems used in centrifugal milk separators. It is shown that direct bearing vibration measurements are more reliable than indirect (through rotor housing) vibration measurements. However, in most cases it is not possible to measure bearing vibrations directly. The factors causing large diagnostic measurement errors, such as the influence of the vibration damping system, step-up gear and electric motor noise are discussed in the paper. It is established that vibration measurements of the damping system are noninformative and cannot be used to diagnose faults in bearings. It is proposed to use the vibration spectra correlation to predict bearing failures in rotor-bearing systems of this type

Spaudos inžinerijos studijų programos metodikos nurodymų rinkinys

Leidinį sudaro šie laboratorinių darbų metodikos nurodymai: J. Sidaravičius „Spausdinimo medžiagos“, J. Sidaravičius „Spausdinimo procesų technologija“, J. Sidaravičius „Spausdinimo ir apdailos įrenginiai“, J. Sidaravičius „Spaustuvė: kompleksinio projekto rengimo metodikos nurodymai“, V. Turla „Brošiūravimo ir įrišimo įranga bei technologija“, V. K. Augustaitis „Ruošimo spausdinti įranga“, V. K. Augustaitis „Ruošimo spausdinti technologija“

The investigation of dynamics of misaligned units in vehicle transmission

In the article the problems related to the dynamics of a mechanic system on misalignment of shafts in radial direction are presented. The object of the investigation is a two-shaft system connected with an elastic centrifugal ring coupling. Using equations of static equilibrium it was found that an internal moment of resistance to rotation appears in the coupling connecting the radially misaligned shafts. Using Dalamber's principle for the rotational movement the differential equation that describes the rotation of the second shaft has been developed. It was shown that after the perfonnance of the corresponding actions and the introduction of a new variable the said equation is transformed in to an equation which character virtually coincides with the equation describing free oscillations of a mathematical pendulum. Because the value of misalignment of shafts in the radial direction is small in comparison with other parameters, a small parameter method was used for the solution of this equation. The found solutions show that rotational vibrations with the double frequency of rotational movement are excited in the misaligned mechanical system with an elastic centrifugal ring coupling. The restrictions ofthe application of a small parameters method have been explored and the limits of its application have been found. First Published Online: 19 Dec 201

Investigation of radial misalignment influence on dynamics of precise rotor system

After presentation of the classification of vibra-tion damping devices for rotation systems developed in Vilnius Gediminas technical university, the problems con-nected with dynamics of rotor system at certain radial mis-alignment of shafts are investigated in the offered work. As object of research is the system of two shafts connected by elastic centrifugal ring coupling. It is established, that in the coupling, connecting radially misaligned shafts, an internal resistance moment to rotation is arising. Using the principle of d’Alamber for rotary movement, the differen-tial equation describing rotation of the second shaft is worked out. The received solutions show, that rotational fluctuations arise in rotating misaligned system. The fre-quency of fluctuations is double the rotation frequency. Results of investigation were applied for rotational vibra-tions reducing of rotor systems

Informacinės technologijos poligrafijoje. Darbas su CorelDRAW

Knygoje pateikiamos bendrosios žinios apie grafinio dizaino elementų komponavimo principus ir pagrindines kompozicijos, meninės raiškos ir harmonizavimo priemones, grafinio dizaino spaudos objektų projektavimo principus bei jų gamybą. Daug dėmesio skirta prekės ženklo ir logotipo kūrimui, aptariamos priemonės, kuriomis pasiekiamas prekės ženklo ir logotipo populiarumas. Atskiri skyriai skirti pakuočių dizainui, analizuojama, kokį poveikį pakuotės ir etiketės dizainas daro prekės pateikimui, reklamos kūrimui ir ergonomikai. Knygą sudaro teorinė ir praktinė (pratimai) dalys, kuriose aptariami konkretūs uždaviniai, aktualūs kompiuteriu dirbančiam dizaineriui. Visi pratimai skirti atlikti CorelDraw CS4 programa. Mokomoji knyga skirta VGTU Mechanikos fakulteto spaudos inžinerijos studijų programos studentams, studijuojantiems rengimo spaudai technologijas ir informacines poligrafijos technologijas. Ja taip pat gali naudotis visi, kurie domisi CorelDraw programinio paketo galimybėmis. Leidinys parengtas ir išleistas už Europos struktūrinių fondų lėšas, jomis finansuojant VGTU Mechanikos fakulteto projektą „Pirmosios pakopos inžinerinių studijų programų atnaujinimas gerinant studijų kokybę, didinant tarptautiškumą ir diegiant inovatyvius mokymo (-si) metodus“ pagal Lietuvos 2007–2013 m. Žmogiškųjų išteklių veiksmų programos 2 prioriteto „Mokymasis visą gyvenimą“ VP1-2.2-ŠMM-07-K priemonę „Studijų kokybės gerinimas, tarptautiškumo didinimas“. Projekto kodas Nr. VP1-2.2-ŠMM-07-K-01-051, finansavimo ir administravimo sutartis Nr. VP1-2.2-ŠMM-07-05

The influence of formulating a damping solution on dot gain

Difference in dot gain using various additives to the damping solution was investigated on two offset web presses. Dot gain was measured using a densitometer and calculated considering CIE L*a*b* coordinates. It was found that while using a non alcohol additive instead of the alcohol one, dot gain became smaller and printing stability was lower. Changes in dot gain depend on the ink that may vary in colours. The influence of changes in dot gain on the colour was determined. Besides, it was found that differences in colour were unacceptable in many cases. Article in Lithuanian Vilgymo skysčio sudėties įtaka rastrinių taškų padidėjimui spausdinant Santrauka Darbe tirta vilgymo skysčio sudėties įtaka rastrinių taškų padidėjimui spausdinant dviem ritininėmis spausdinimo mašinomis. Taškų padidėjimas matuotas densitometru ir skaičiuotas pagal CIE L*a*b* koordinates. Nustatyta, kad pakeitus spiritinį vilgymo skysčio priedą nespiritiniu rastrinių taškų padidėjimas sumenksta ir sumažėja spausdinimo stabilumas. Taškai padidėja nevienodai esant skirtingoms spalvoms. Taip pat ištirta, kad rastrinių taškų didėjimo pokyčiai keičiant vilgymo skysčio priedus iškraipo spalvas ir daugeliu atvejų spalvų skirtumai būna neleistino lygio. Reikšminiai žodžiai: taško dydis, rastrinio taško padidėjimas, spalvų parametrų kitimas