Real time production monitoring systems (PMSs) is an alternative to manual data collection and captures most of the required production data without human intervention. The general objective of the current study is to analyse PMSs and to offer particular solutions for small and medium sized enterprises (SMEs). The subtasks to be solved in the case of each particular PMS include determining relevant parameters, designing PMS and development of the data analysis and prognosis model for short term and long term planning. The selection of suitable PMS components and relevant parameters and the development of lathe cutting unit measuring system are described in the case study. Defendec Inc. and National Instruments Corporation wireless components were adopted to implement a part of the PMS.
Water and air temperatures during 1980-2010 were compared at three coastal stations of Estonia with the aim to estimate the stability conditions of the lower layers of the atmosphere. It is shown that the difference between the air and water temperatures varies during the year and the annual cycle of this variation is different at different measurement sites and also during different wind directions. Measurements at Sorve demonstrate an unusual situation when the air-sea temperature difference is affected by the wind systems of the Gulf of Riga and Baltic Proper.
The classical wave equation is a cornerstone in mathematical physics and mechanics. Its modifications are widely used in order to describe wave phenomena. In mechanics deformation waves are related to impact problems, acoustic waves are used in Nondestructive Evaluation, seismic waves may cause a lot of damage, etc. In this paper it is shown how the classical wave equation can be modified in order to model better the physics of processes. The examples cover microstructured and inhomogeneous materials together with linear and nonlinear models. Beside usual two-wave models, the evolution equations are described which govern the distortion of a single wave.
Processes are very fast in contemporary dynamic, turbulent and continually changing world. Systems supporting these processes become more and more complicated and are in mutual interaction. Design of high performance workplaces becomes more and more important for achiev- ing competitiveness. In the current article workplace capability, formed by capability of techno- logical resources and human resources, as well as lean manufacturing principles are analysed with an aim to design high performance workplaces.
The author ponders about things that necessarily come into engineering mind when the results obtained by theoretical, numerical and experimental approaches in solid continuum mechanics are correlated and compared with a pious wish to ascertain which of them are 'truer' or closer to 'reality'.This invokes many questions.How ancient and contemporary philosophers viewed the truth?How is truth related to consistency and validity of theoretical, numerical and experimental models we are inventing and employing?What is the role of threshold in physics, engineering, computation and in experiment?How are the basic quantities like time, force, stress, etc. defined?Do we properly understand them?What is the role of singularity in mathematics, physics and in engineering?The doubts stemming from uneasy answers to above pertinent questions are complemented by discussing examples from theoretical, numerical and experimental results obtained by solving dynamical problems in solid continuum mechanics.It should be stressed out that the role of doubts in our understanding the World plays a significantly positive role.
This paper presents new refined mathematical, Simulink and function block models for mobile robots, and some considerations regarding mechatronics design and control solutions. The presented models are mainly intended to be used to help in facing the two top challenges in developing mechatronic mobile robotic systems: firstly, early identifying system level problems and ensuring that all design requirements are met, and secondly, to be used for research purposes and application in educational process. The presented models, blocks and designs were created and verified using MATLAB/Simulink software. Testing models for achieving desired design specifica- tions shows the applicability and accuracy of the design. The results also show that PID, PI and PI with deadbeat response are applicable for achieving desired smooth speed of a given mobile robot with acceptable stability and fastness of response.
A case study of the first nearly zero energy office building (nZEB) in Rakvere, Estonia was conducted to determine whether an office building can be built without a conventional space heating system while ensuring adequate thermal comfort in the offices. Energy and indoor climate simulations of alternative solutions were carried out and the feasibility of the solutions, ensuring heated rooms throughout the year, was assessed based on investment cost and payback calculations. The results showed that despite of the low heat losses, a nZEB still needs a space heating system with room based temperature control. Heating needs primarily occurred during weekends and at night; however, without space heating the air temperatures in the rooms dropped down to 16.7 °C during occupancy and were below 21 °C during about 700 occupied hours. Supply air heating with variable air volume system, controlled according to the coldest room and on demand night operation, was able to keep + 21 °C temperature in all rooms, but resulted in significant energy penalty caused by overheating of offices with lower heat losses and increased fan electricity use. The economic analysis showed that a building with simple constant air volume ventilation system and radiator heating was most feasible. The investment cost increase of the variable air flow ventilation system was too high compared to the savings in energy cost that was already low.
Cross-shore beach profiles along Estonian coasts of the Baltic Sea are analysed from the viewpoint of the frequency of occurrence of convex sections that may support non-reflecting wave propagation and unexpectedly high run-up events. In total 194 beach profiles, measured in 2006- 2011 at 16 locations, are examined by means of their approximation with the power function () . b hx Ax = About half of the profiles can be adequately approximated using a single power function. These profiles are almost all concave. The relevant exponents are clustered around b = 2/3 that is characteristic to the Dean's Equilibrium Profile. The rest of the profiles can be divided into two sections, each of which is approximated by a power function. The underwater sections of such profiles predominantly match the Dean's Equilibrium Profile. About 10% of the subaerial sections (about 7% of all examples) have the exponent close to b = 4/3, for which high run-up events are likely.
The present paper is devoted to the problem of measuring and modelling the changes in human motor functions. Nowadays, overwhelming majority of techniques for motion analysis and gesture recognition are based on feature extraction, pattern recognition and clustering. An alternative approach to measure and model changes in motor functions is proposed. Unlike feature extraction or pattern recognition techniques, the proposed approach concentrates its attention on the total quantity and smoothness of the human limb movements. The latter constitutes the main distinctive feature of the proposed technique. When changes of human motor functions are caused by learning of a new motor activity, amount and smoothness of the movements may provide necessary information to measure the effectiveness of the training technique. The notion “motion mass” is introduced as a measure associated with the motion, which describes how much and how smoothly certain joints have moved. Practical example of learning the ball throwing is used to demonstrate the ability of the proposed approach to measure the changes in motor functions and distinguish their performance on different stages of the learning process.
In the current article, high-velocity oxy-fuel (HVOF) sprayed composite powder TiC- NiMo and Cr3C2-Ni cermet particles reinforced self-fluxing alloy matrix (FeCrSiB) coatings were studied. The actual content of the reinforcement in the sprayed coatings was smaller in comparison with the feedstock powders. Cermet particles were deformed at the impact with the substrate, deformation was more remarkable in the case of the TiC-NiMo particles. Sprayed coatings exhibited a structure with a number of defects, like voids and cracks, whereas the latter were more pronounced in reinforced coatings. Despite the bigger number of defects, cermet particles reinforced coatings had up to 1.2 times higher surface hardness than the unreinforced coating. TiC- NiMo particles reinforced coating demonstrated 1.8 times higher sliding wear resistance than the unreinforced coating. Cr3C2-Ni particles reinforced coating showed 1.3-2.8 times higher sliding wear resistance in comparison with the unreinforced coating, depending on the series of tests. Addition of cermet particles allowed to increase the resistance of the FeCrSiB matrix to deformation and scuffing.
The closure depth is a key parameter in coastal processes as it characterizes the overall wave intensity in the nearshore and indicates the water depth down to which storm waves are able to maintain a universal shape of equilibrium coastal profiles. The properties and alongshore variations of the closure depth for the eastern Baltic Sea coast are evaluated at a coarse resolution (5.5 km) and for the vicinity of Tallinn Bay at a higher resolution (0.5 km). The study is based on numerical simulations of wind-generated wave fields. It is shown that, due to the small contribution of remote swell in the Baltic Sea, the typical ratio of wave heights in strongest storms and average wave heights is about 5.5, which departs considerably from that of open ocean coasts. A modification of the formula for the approximate calculation of the closure depth from the average wave height is derived. The estimates are based on four methods: from the wave heights of the strongest storms, from average wave heights based on a linear approximation, and using two versions of a second-order approximation. The greatest closure depth of up to 7.25 m was found to occur along the coast of the Baltic Proper near Hiiumaa, Saaremaa and the Kurzeme Peninsula. These areas also experience the largest wave intensities. Along other parts of the Baltic Proper coast the closure depth is typically 5-6 m, whereas in the Gulf of Riga and along the southern coast of the Gulf of Finland it is usually in the range of 3-4 m.
The basic concepts for modelling wave propagation in solids with microstructure are described. It is shown that the Green method, based on postulating the potential energy function, has certain advantages compared with the widely used Cauchy method, which postulates directly the stress-strain relations. Simple examples demonstrate how the Green method together with internal variables permits to determine the microstress and the interactive force between the constituents of solids. The structure of governing equations and possible physical effects captured by such modelling are described. The microstress and interactive force lead to the dispersion of waves at the macrolevel.
Direct nitridation of hexagonal aluminium nitride (AlN), using additive like NH4Cl, was performed from Al metal powder. Different methods of AlN synthesis, viz. a) Al powder, b) Al and NH4Cl, c) Al and NH4Cl with urea, were carried out in continuous flowing of N2 gas at 900 °C for 5 h. The synthesized powder was characterized by employing TGA/DTA, XRD, FTIR, SEM, UV- VIS Spectroscopy and CHNS analysis. The mechanism for the formation of AlN by the influence of additive and role of urea are discussed.
Estonian cost optimal and nearly zero energy building (nZEB) energy performance levels were determined for the reference detached house, apartment and office building. Cost optimal energy performance levels, i.e. the energy performance leading to the lowest life cycle cost according to defined methodology, are implemented into new Estonian energy performance regulation as minimum requirements for new buildings. The regulation that came into force since 9 January 2013 includes requirements for nZEB buildings, but they are not mandatory. Compared to previous requirements, cost optimal requirements improve energy performance by 20%-40% depending on the building type and energy sources used. The results of the reference office and apartment building are reported. The results of the reference detached house, being previously reported, have been recalculated with new energy carrier factor for electricity, which was one major change in the regulation in addition to new requirements. When the detached house showed global cost curves with well-established cost optimal points, global cost curves were much more flat for the apartment and office building. This indicates that the results are sensitive to input data and relatively small changes in input data can significantly shift the cost optimal points. As uncertainties related to nZEB performance level and cost calculation are generally much higher due to high performance technical solutions not commonly used and costs not well established, it is recommended to repeat nZEB calculations with possibly refined input data before setting mandatory nZEB requirements.
The demand to fulfil a wider range of customer requirements is increasing constantly as well as the need for the customizable production tools. At the same time, the product life cycle as well as the lead time for product development shortens. To respond these changing needs, digital product development enables faster development of complex products but challenges the communication and the data management. Digital design methods and manufacturing processes enable this development and decrease the need for expensive prototyping. In this research, digital design and manufacturing process means such a process where design and manufacturing can be done even over long distances between physical location of designers and the production line. An empirical case study of a configurable bathroom faucet was performed. The digital design for manufacturing using sand casting and laser additive manufacturing as alternative digital manu- facturing technologies were researched in this study as possible methods for manufacturing these configurable products.
Management innovation scholars over the last decade and quality management authorities over several past decades have indicated that companies need effective management practices in order to utilize complex automated systems. However, empirical evidence for a relationship between companies' management and technological capabilities has been lacking. This study plugs an important gap in empirical evidence of the relationship between companies' management capabilities and application of complex automated systems. A pilot study was conducted in Estonian companies, which apply robot welding. Evidence of a strong correlation (correlation coefficient of 0.74) between companies' management capabilities and effectiveness in utilizing this complex technology was shown. The study also revealed a novel survey instrument for studying companies' management and technological capabilities.
This paper describes a hybrid control structure, working scenarios and logic of working cycles during the assembly of an unlimited sequence of assembly orders in a bionic assembly system (BAS). Focus is given on the realization of the communication between subsystems, different modes of the assembly process and scheduling strategies and basic tasks of mobile robots during assembly. BAS is a new concept in advanced assembling systems, which combines two basic control structures and principles: a centralized control system, based on the hierarchy, and a self-organizing control system, based on the heterarchy.
In the present article actual matters of technological innovations are dealt with in the context of research universities, mainly taking into account the circumstances in Estonia. One of the cognitive models of the process of technological innovation has been presented. Patents are an integral part of technological innovation, notably in the case of development of new products. The patent statistics given in the article shows that despite wishes the business sector and universities not enough oriented internationally.
The aim of this experimental study is to evaluate the tool life of each cutting material used in dry hard turning of AISI H11, treated at 50 HRC. This steel is intended for hot work, is free from tungsten on CrMoV basis, insensitive to temperature changes and has a high wear resistance. It is employed for the manufacture of the moulds and inserts, module matrices of car doors and helicopter rotor blades. The tests of straight turning were carried out using the following cutting materials: carbides (H13A and GC3015), ceramics (mixed CC650 and reinforced CC670) and cermets (CT5015 and GC1525). Experimental results enable us to study the influence of machining time on flank wear VB of these cutting materials and to determine their lifespan for this cutting regime (depth of cut ap = 0.15 mm, feed rate f = 0.08 mm/rev and cutting speed Vc = 120 m/min). It arises that mixed ceramic (insert CC650) is more resistant to wear than cutting materials. Its tool life is 49 min and consequently, it is the most powerful.
