Scalable surface microstructuring by a fiber laser for controlled nucleate boiling performance of high- and low-surface-tension fluids

Nucleate boiling enables effective cooling and heat transfer at low temperature differences between a heated surface and the surrounding fluid. It is utilized in many applications, ranging from large power plants to small microelectronics. To enhance the boiling process by minimization of the surface temperature and increase the maximum attainable heat flux, several approaches for surface modifications were recently developed. However, each of them has at least one important drawback, including challenging and expensive production, mechanical and/or thermal instability or problematic scale-up. Herein, a straightforward, robust and flexible method using a nanosecond fiber laser for production of surfaces with multi-scale micro-cavities (with diameters ranging from 0.2 to 10 µm) is developed. Examination of these surfaces in two very contrasting fluids - water, which is polar, has high surface tension and high latent heat of vaporizationand non-polar, dielectric tetradecafluorohexane (FC-72) with low surface tension and much lower latent heat - confirms that such surfaces enable enhanced heat transfer and controlled boiling in combination with diverse fluids. This demonstration suggests that the developed method has the potential to overcome the current limitations for further miniaturization of microelectronic devices and to increase performance and safety in high heat flux systems

The concretization of the term sustainable spatial development for the assessment of child and juvenile awareness

The following article is targeted at the comprehensive co-shaping of the conditions required for the active education on the effective and concrete contributions to sustainable development, with the emphasis based on the built environment or architecture. It defines the role of education on the built environment or architecture within the concept of sustainable development, determines the grounds for adjusting the methods of delivering architectural contents and defines the educational contents along with their presentations with regards to the developmental abilities of the public, which is targeted. It presents the deliberation on objectifying the term sustainable spatial development, for the assessment of child and juvenile awareness of “sustainable architecture” topics as well as determining childcare workers and teachers adequate qualifications to provide the knowledge in the field of the built environment, in relation to sustainable environment. Concretisation signifies the selection and visualisation of actual topical occurrences in physical space for a specific targeted public (the article provides representative models). It also contributes to the development of “cultural” dimension of spatial development sustainability. The efforts made to strive towards the lifelong learning of architecture and its influence on our everyday lives and our future

Konkretizacija pojma trajnostnega prostorskega razvoja za oceno osveščenosti otrok in mladostnikov

Prispevek je usmerjen k celovitemu sooblikovanju pogojev za tvorno izobraževanje o učinkovitih, konkretnih prispevkih k trajnostni razvojni usmeritvi, s poudarkom na grajenem okolju oziroma arhitekturi. Opredeljuje vlogo izobraževanja o grajenem okolju oziroma arhitekturi v konceptu trajnostnega razvoja; določa izhodišča za prilagajanje načinov posredovanja arhitekturnih vsebin ter opredeljuje izobraževalne vsebine in njihove predstavitve glede na razvojne sposobnosti ciljne publike. Predstavlja torej razmislek o opredmetenju pojma trajnostni prostorski razvoj za oceno osveščenosti otrok in mladostnikov o »trajnostnih arhitekturnih« temah ter tudi za ugotavljanje usposobljenost vzgojiteljev in učiteljev za posredovanje znanja s področja grajenega okolja v povezavi s trajnostnim razvojem. Konkretizacija pomeni izbor in vizualizacijo aktualnih konkretnih pojavov v prostoru za izbrano ciljno publiko – v prispevku so prikazani vzorčni primeri. Prispeva k razvoju »kulturne« dimenzije trajnosti prostorskega razvoja. Prizadevanja vodijo k razvoju sistema vseživljenjskega učenja o arhitekturi ter njenem vplivu na naš vsakdan in naš jutri

Kvint Tulij Ciceron: Mali priročnik za volilno kampanjo

Domnevni avtor besedila je Kvint Tulij Ciceron, brat slavnejšega Marka. Leta 64 se je Mark kot novinec »homo novus« potegoval za konzulat. Nasproti so mu stali razvpiti nasprotniki, kot sta bila Katilina in Antonij, oče Marka Antonija. Kvint naj bi mu bil ob tej priložnosti napisal priročnik za volilno kampanjo v obliki pisma. Zelo verjetno je Kvint res napisal neki spis s tem naslovom, zaradi mnogih spornih mest in anahronizmov pa ni dokazano, da je to ravno tisto besedilo.   Pri prevajanju so sodelovali še Jurij Frice, Tina Bernik, Maja Gril, Sonja Ljubetič in Špela Tomažinčič

Vizualni jezik predstavitve prostora – ovira ali stičišče? Povečanje učinkovitosti posredovanja idej o prostoru med splošno in strokovno javnostjo

Prispevek obravnava tehnike predstavljanja arhitekturnih in urbanističnih idej o prostoru ter njegovih spremembah. Poglablja se v proces sporazumevanja med sooblikovalci prostora in usmerja v problematiko razlik v razumevanju vizualnega jezika predstavitev, ki izhajajo iz različnih ravni sposobnosti vizualnega izražanja in razumevanja vizualnih sporočil. Poudarja problem nezavedanja posebnosti strokovnega jezika kot posledico navajenosti nanj. Predstavljena raziskava preverja in analizira vpliv abstraktnosti/konkretnosti vizualnih predstavitev na njihovo učinkovitost pri posredovanju sporočil splošni in strokovni javnosti. Ob razpravi o dognanjih se odpirajo številna nova vprašanja o možnostih zbliževanja različnih javnosti in iskanja skupnih točk. Prispevek med različnimi rešitvami za izboljšanje sporazumevanja med udeleženci pri sooblikovanju prostora izpostavlja potencial trajnega izobraževanja. A ne gre le za izboljšanje splošnega razumevanja vizualnega jezika, temveč posledično razmišlja o načinih, posrednikih in njegovih pozitivnih posledicah za kulturno okolje in prostorsko kulturo

The visual language of spatial representation – a barrier, or a crossroad?

The article deals with techniques of representation of architectural and urbanistic ideas about space and its changes. It delves into the communication process between co-creators of space and points out the issue of different understanding of visual representation techniques that stem from different levels in capabilities of visual expression and understanding of visual messages. The issue of ignorance of specifics of professional language is emphasised as a consequence of its habitualness. The presented research checks and analyses the effect of abstract/concrete visual representation and their effectiveness in communicating messages to expert and lay publics. Following the discussion about results, numerous new issues arise, concerning possibilities for narrowing the gap between various publics and finding common ground. Amongst different solutions about improving communication between actors in the creation of space, the article emphasises the potential of permanent education. However the quest is not for improvements in general understanding of visual language, but consequentially to devise ways, modes and their positive consequences on the cultural environment and spatial culture

Pridobivanje električne energije preko izkoriščanja naboja v vodnem stolpcu

Zaradi vse večjega pomanjkanja naravnih surovin in hkratnega povečevanja potreb po energiji je želja po učinkoviti izrabi obnovljivih virov energije neprestana. V raziskavi smo preučevali pridobivanje električne energije na podlagi črpanja električnega naboja, ki se tvori ob čepastem toku kapljevine znotraj neprevodne cevi. Na podlagi obstoječih znanstvenih raziskav smo izdelali delujoč koncept ter izvedli meritve pri različnih kemijskih sestavah in električnih prevodnostih testne kapljevine. Poleg različne kemijske sestave smo preverjali tudi vpliv vsebnosti mehurčkov na generacijo električne energije. Kljub nekaterim ugotovitvam, da bo večja električna prevodnost kapljevine zaradi večje koncentracije ionov doprinesla k več večji energiji, rezultati te študije nazorno kažejo, da večji tokovni in napetostni pulz generirajo ravno slabo prevodne kapljevine

Pattern geometry optimization on superbiphilic aluminum surfaces for enhanced pool boiling heat transfer

In this study, the optimal surface pattern of low and high wettability regions for enhanced boiling heat transfer is investigated using aluminum superbiphilic surfaces. Samples are fabricated by combining chemical vapor deposition of a fluorinated silane to turn them superhydrophobic and nanosecond laser texturing to render selected areas superhydrophilic. Triangular lattice pattern of superhydrophobic circular spots is utilized with spot diameters between 0.25 mm and 1.0 mm and pitch values of 0.5-2.5 mm. Pool boiling heat transfer performance of superbiphilic surfaces is evaluated using saturated water at atmospheric pressure. A strong wettability contrast is shown to be important in ensuring high heat transfer performance of wettability-patterned surfaces. Highest heat transfer performance is achieved using 0.5 mm diameter spots with a spot pitch of 1 mm and a corresponding superhydrophobic area fraction of approx. 23%. The optimal pitch value will provide a high density of potentially active nucleation sites but still allow for the development of the thermal boundary layer thus not inhibiting the activation of neighboring spots. The size of (super)hydrophobic spots appears not to have a major influence on the boiling performance when using the optimal spot pitch. The developed superbiphilic surfaces increase the CHF and provide greatly enhanced heat transfer coefficients especially at medium and high heat fluxes, making them suitable especially for high-heat-flux applications