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The Detection of Nut Driver's Optimal Working Regimes Taking into Account Power Consumption and Assembly Time during Fixed Threaded Joints Assembly
No full textIn given article the nut driver's electric power consumption studies depending on the corresponding fixed threaded joint's assembly time are made. So far there are no recommendations from the tool manufactures for nut driver's optimal operating modes (the conclusion is made based on the attached instructions which provide instrument manufacturers), when evaluating this aspect taking into account the electrical power consumption and assembly time for different types of fixed threaded joints (wood, metal, plastic, etc.) and also taking into account obtainable tightening moments. In the examined literature sources which deal with the opportunities concerning the optimization of the automated assembly processes of fixed threaded joints, not enough attention is paid to the reduction of the instrument's energy consumption which is one of the main tasks in the industrial process because it directly impacts production costs
Research of Influence of Collected Details form Deviation on the Accuracy of Precision Assembly
No full textIn this article are described the component parts of technological maintenance of assembly of the precision pairs, which have an influence on the assembly quality of pairs and possibility of realization of assembly process. For achieve this goal authors suggest solving two tasks: research the influence of form deviations and the influence of camber of axis of the parts on the technological process of assembly of precision pairs. In the result in given article it is shown that at the automated precision assembly it is possible not to measure a form deviation of the details, but sort them, using inexpensive means of certification of the details size
Zemes izmantošanas efektivitātes novērtēšanas metodoloģija zemes pārvaldībā
No full textDarbā raksturotas zemes izmantošanas problēmas, parādīta efektivitātes nozīme zemes pārvaldībā, izpētīta zemes izmantošanas mērķu attīstība un rezultātu ietekme uz Latvijas tautsaimniecību, izvērtētas zemes izmantošanas klasifikācijas problēmas un zemes pārvaldības institūciju darbība, sniegts dažādu valstu zemes pārvaldības sistēmu analītisks vērtējums un zemes izmantošanas efektivitātes rezultatīvais vērtējums dažādos zemes pārvaldības līmeņos, noteikts zemes izmantošanas rezultātus ietekmējošo faktoru izmaiņu raksturs un tendences, kā arī norādīti identificēto zemes izmantošanas problēmu risināšanas virzieni.
Darbā analizēti zemes izmantošanas efektivitātes novērtēšanas teorētiskie aspekti ilgtspējīgas zemes pārvaldības ietvarā, izpētīta zemes izmantošanas reglamentācijas vēsturiskā attīstība un zemes izmantošanas efektivitātes sociāli ekonomiskais un ekoloģiskais saturs, sniegtas nozīmīgāko jēdzienu un terminu definīcijas, noteikti zemes izmantošanas efektivitāti ietekmējošie faktori un novērtējamās pazīmes, apkopotas un izpētītas dažādas zemes izmantošanas efektivitātes novērtēšanā lietojamās metodes un identificēti rādītāji, kā arī izveidots zemes izmantošanas efektivitātes novērtēšanas ietvara modelis un piedāvāta rādītāju sistēma.
Darbā iekļauti zemes izmantošanas efektivitātes novērtēšanas metodoloģiskie risinājumi un apkopoti veikto pētījumu rezultāti, sniegta zemes izmantošanas novērtēšanas pieredze un zemes izmantošanas efektivitāti raksturojošo rādītāju analītisks vērtējums un lietošana, kā arī pamatota zemes izmantošanas efektivitātes novērtēšanā lietojamo metodoloģisko risinājumu, atsevišķu metožu un rādītāju sistēmas praktiska izmantošana.
Darba nobeigumā ietverti pētījuma rezultātā iegūtie galvenie secinājumi un priekšlikumi.
Galvenais darba secinājums — izstrādāta un zinātniski pamatota metodoloģija zemes izmantošanas efektivitātes novērtēšanā ir nepieciešama pastāvīgai zemes resursu izmantošanas pārraudzībai un lēmumu pieņemšanai, lai veicinātu šo resursu lietderīgu un ilgtspējīgu izmantošanu sabiedrības interesēs.
Darbs izklāstīts uz 203 pamatteksta lappusēm un 11 pielikumiem. Promocijas darba izstrādes gaitā ir izmantoti vairāk kā 300 dažādi informācijas avoti, no kuriem 216 ir iekļauti darba bibliogrāfiskajā sarakstā
Experimental Investigation of Weft Knitted Fabric Layered Reinforcement Efficiency in Fiberconcrete
No full textReinforcing cement-based composites with continuous fibers is one of the most efficient ways to obtain high performance materials. In this paper a layers of knitted textiles with relatively simple fabric architecture was used to strengthen fiberconcrete beams. The objective of this study was to evaluate glass knitted fabric as reinforcement for fiberconcrete. For this purpose fiberconcrete beams with textile reinforcement in a form of three plies of glass weft knitted fabric (jersey) were produced. Four point bending test was used to experimentally investigate influence of textile plies on composite flexural strength. Obtained results were compared with material without textile reinforcement. The fiberconcrete reinforced by textile layers showed better flexural performance compared to non-reinforced fiberconcrete samples
Environmental Aspects and Operation Mode of Small Hydropower
No full textThe use of renewable sources must be balanced with environmental aspects. Especially it relates to the use of river water flow. Environmental requirements are hard to achieve on large hydropower. Much hydro are built and yet can be built on small rivers, usually building the dams which create small lakes and prevent movement of fauna along the river. In places of large inclination of river channel the dam can be substituted by water ducts, such as pipes. The movement of water in the pipe meets resistance and some part of water pressure is lost. There is little resistance to movement of water by laminar flow of water but this flow exist by small velocities of water. So it can be counted on turbulent flow. By a given diameter of pipe the maximum power can be get when 1/3 of the water pressure is used on water movement in the pipe. The cost of pipe is proportional to pipe length multiplied by the root of fifth degree of the pipe length. Artificial rapids can be made which reduce pipe length. Such a hydro must be connected to a grid. It operates in the rhythm of the river
Impact of Distributed Generation on Current and Impedance Protections
No full textDistributed generators (DG) are scattered throughout the countryside. As a result, they are of relatively small power and should be connected without commutating apparata to low and medium voltage radial power lines. The protection of this power line loses accuracy. To what extent current or distant protection is impaired, depends on many factors. The negative impact of DG is characterized by setting ratio (SR): the relation of current or impedance setting with DG to these quantities without DG. SR depends primarily on DG fault quotients – the fault current of separate DG divided by total fault current of main source and all DG connected to this radial line. Usually DG fault quotients are greater than DG load shares and grow to the end of radial line. SR are worse when fault quotients increase along the line. Head current protection and head distance protection and intermediate distance protections have underreach when DG fault quotients are not very different. For head protection, impedance SR is inverse of current SR and improves when protection is installed nearer to the fault. Current limiting reactors in series with DG improve SR
Capacitance and Leakage Current Balancing for Supercapacitive Energy Storage System
No full textIn the paper, the problem of voltage imbalance in supercapacitor bank caused by different
capacitances and leakage resistances is considered. The authors propose capacitance balancing in
combination with passive resistor voltage balancing as an efficient method for decreasing the cell
voltage imbalance and increasing the effective energy capacity of supercapacitor bank. The
efficiency of the method is demonstrated theoretically and verified experimentally on eight
supercapacitor cells
RRTs Postprocessing for Uncertain Environments
No full textPath planning is one of the central tasks to be
solved in mobile robotics. Rapidly Exploring Random Tree is
one of possible alternatives addressing path planning. While it
does not deliver optimal solution it provides a good
performance that is crucial for most cases in mobile robotic
systems. Unfortunately the algorithm may produce
unnecessary or even dangerous waypoints that might lead to
collisions with obstacles or other robotic systems. A significant
part of the possible collisions are caused by uncertainty of
robot positioning or obstacle sensing. In this paper we propose
a set of plan post processing steps to estimate and decrease the
possibility of collisions during plan executio