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Inventory Management with Variable Lead-Time Dependent Procurement Cost
No full textA reduction in the inventory replenishment lead-time allows reducing safety stock requirements and improving customer service. However, it might be accompanied by increased procurement costs because of premium charges imposed by suppliers, or higher transportation costs. This paper studies a single-stage variable lead-time inventory system with lead-time dependent procurement cost. Selection of the lead-time value represents finding the trade-off between benefits of lead-time reduction and increase in the procurement cost. A model for joint optimization of inventory and procurement costs is developed. Numerical studies are conducted to identify conditions under which lead-time reduction is favorable compared to procuring at the lowest cost
The Importance of Clothing Fashion Show in the Study Process
No full textPēdējo gadu laikā arvien vairāk Rīgas Tehniskās universitātes absolventu kļūst par ārzemju apģērbu firmu kvalificētiem dizaineriem. Izpratni par mākslinieciskās novitātes lomu un potenciālo pircēju un ražošanas prasību ievērošanas nozīmi rūpniecisko kolekciju veidošanā jaunie speciālisti apgūst 4 gadu studiju laikā. Studiju beigu darbā studentiem gan jāizstrādā apģērbu kolekcija, gan tā publiski jāprezentē modes skatē. Kolekciju publiska vērtēšana paaugstina studentu atbildības pakāpi par savu darbu un līdz ar to uzlabo šo darbu kvalitāti. Studentiem nopietni jāplāno kolekcijas izstrādāšanas secība, materiālu, modeļu atlase un savstarpējā komplektācija, darbs ar modeļu demonstrētājiem kolekcijas izgatavošanas un prezentācijas laikā, jāatrod optimāls vizuālais un muzikālais skates noformējums. Kolekcijas sagatavošana publiskai demonstrācijai modes skatē maksimāli tuvina projektēšanas darbu pamatprincipus un secību reāliem kolekcijas izstrādāšanas apstākļiem apģērbu tirgū. Jaunajiem speciālistiem tā ir pirmā pieredze rūpnieciskas kolekcijas izstrādāšanā
Electronic States Spectroscopy of Hydroxyapatite Ceramics
No full textPhotoluminescence, surface photovoltage spectroscopy and high-resolution characterization methods (Atomic Force Microscopy, Scanning Electron Microscopy, X-ray spectroscopy and DC conductivity) are applied to nanostructured Hydroxyapatite (HAp) bioceramics and allowed to study electron (hole) energy states spectra of the HAp and distinguish bulk and surface localized levels. The measured trap spectra show strong sensitivity to preliminary heat treatment of the ceramics. It is assumed that found deep electron (hole) charged states are responsible for high bioactivity of the HAp nanoceramics
Nanostructured Composite Coatings for the Protection and Restoration of Precision Friction Pair Parts
No full textThe paper deals with the creation of fundamentally new functional multicomponent coatings applying the technologies of ion-plasmous sputtering. Developed a restoration technique for the precision pairs of hydro fuel equipment. The obtained coatings are peculiar because of their enhanced wear resistance, low coefficient of friction, and good adhesion with basic material
Information Communication Technologies in Architectural Education
No full textNowadays Computer Aided Architectural Design (CAAD) undoubtedly is recognized as a design media
rather than a design tool and is widely accepted in architectural practice. The general goal architects want is to visually
express design and illustrate their projects or ideas using both professional experience and personal computerized
creative skills. Currently rapid advancements in the growth of information technology which are used to communicate
architectural design projects. CAAD is a particularly dynamic field that is developing through the actions of architects,
software developers, researchers, technology, users and society alike. The paper deals with the teaching of information
technology in architectural schools. The delivery of CAAD knowledge is discussed. Academic courses basically are about
the development of computer aided creative and problem solving skills in context with fast changing CAAD media. It is
more difficult to teach the common principles behind the software which are general and will most likely survive everchanging
software versions. Limited credit points for the subjects do not allow developing detailed courses for training
particular software. An evaluation of the promptitude of the architectural students at Riga Technical University for the
self-sufficient problem solving tasks was performed. Four different computer based design tasks were given to the
students using the same massing model of building. The statistical analysis regarding an average time required to
complete the exercises and correlations between different skills is presented at the conclusion. Further developments of
architectural problem solving are discussed for implementation into the education syste
Application of Software SPRING and Method of Complete Bifurcation Groups for the Bifurcation Analysis of Nonlinear Dynamical System
No full textThe article is devoted to the parametrical analysis of periodic and chaotic oscillations in the nonlinear dynamical systems. Description of the systematic approach to the construction of bifurcation diagrams is offered to your attention. Considered approach allows us to build complete bifurcation diagrams. These diagrams allow to find and investigate regimes, analysis of which is inaccessible by traditional methods. Such approach is used in the method of complete bifurcation groups and realized in the software SPRING. Description of method of complete bifurcation groups and results of using of this method for the parametric analysis of the nonlinear dynamic systems is presented in this article
Modified Alder Wood as a Raw Material for Production of High Density Activated Carbon
No full textThe soft textured wood of grey alder (Alnus incana), is out of demand due to its low technical properties. In the present study, the feasibility to convert this easy-procurable raw material to high-density activated carbon sorbents has been investigated. During steam treatment by high temperature autohydrolysis, the wood was converted into a self-bonding material. By moulding, carbonization and steam activation, activated carbon boards with good mechanical properties were obtained
Cilvēka žokļa kompakto kaulaudu šļūde
No full textDarbā pētīta cilvēka apakšžokļa kompakto kaulaudu aktīvā šļūde ilglaicīgās statiskās spiedes eksperimentā. Paraugi iegūti no pieciem 49 līdz 56 gadu vecu cilvēku apakšžokļiem. Eksperimentu rezultātā noteiktas šļūdes deformācijas, kuru lielums ir atkarīgs no parauga lokalizācijas un sprieguma. Šļūdes deformācijas eksperimentālie dati 15 paraugiem tika aproksimēti ar eksponenciālo funkciju divos variantos – ar divām un trim eksponentēm, katram paraugam atsevišķi. Novērtējot iegūtos rezultātus, atmesti paraugi ar krasi atšķirīgiem datiem, ko var saistīt ar mehānisko un bioloģisko faktoru ietekmi. Aproksimējot paraugu grupu ar divām un trim eksponentēm un kopējām šļūdes vienādojuma konstantēm, labi rezultāti tika iegūti 5 paraugiem. Iegūtos rezultātus var izmantot apakšžokļa kaula matemātiskā modeļa izstrādāšanai, ar mērķi optimizēt un uzlabot ārstēšanas procesu
Transition from ESKD to ISO EN
No full textThe article focuses on the issue of ISO and EU standards adapted in Latvia and corresponding to ESKD 3rd group standards in terms of contents. These standards deal with regulations on technical drawings making the basis of the subject of “Engineering Graphics”.
The article provides a historic insight on the development of Latvian standardisation institutions, their tasks and organisational structure.
Also, the article analyses the situation in the area of publishing study literature developed according to Latvian standards
Rare Attractors and Rare Phenomena in Nonlinear Dynamics
No full textMaterials of the International Symposium RA08 “Rare Attractors and Rare Phenomena in Nonlinear Dynamics” held in Riga-Jurmala, September 8-12, 200