An investigation into the thermophysical and rheological properties of nanofluids for solar thermal applications

Considered to be the next generation of heat transfer fluids, nanofluids have been receiving a growing amount of attention in the past decade despite the controversy and inconsistencies that have been reported. Nanofluids have great potential in a wide range of fields, particularly for solar thermal applications. This paper presents a comprehensive review of the literature on the enhancements in thermophysical and rheological properties resulting from experimental works conducted on molten salt nanofluids that are used in solar thermal energy systems. It was found that an increase in specific heat of 10–30% was achieved for most nanofluids and appeared independent of particle size and to an extent mass concentration. The specific heat increase was attributed to the formation of nanostructures at the solid–liquid interface and it was also noted that the aggregation of nanoparticles has detrimental effects on the specific heat increase. Thermal conductivity was also found to increase, though less consistently, ranging from 3% to 35%. Viscosity was seen to increase with the addition of nanoparticles and is dependent on the amount of aggregation of the particles. An in-depth micro level analysis of the mechanisms behind the thermophysical property changes is presented in this paper. In addition, possible trends are discussed relating to current theorised mechanisms in an attempt to explain the behaviour of molten salt nanofluids.

Statistical tools for analyzing water quality data

Water quality data are often collected at different sites over time to improve water quality management. Water quality data usually exhibit the following characteristics: non-normal distribution, presence of outliers, missing values, values below detection limits (censored), and serial dependence. It is essential to apply appropriate statistical methodology when analyzing water quality data to draw valid conclusions and hence provide useful advice in water management. In this chapter, we will provide and demonstrate various statistical tools for analyzing such water quality data, and will also introduce how to use a statistical software R to analyze water quality data by various statistical methods. A dataset collected from the Susquehanna River Basin will be used to demonstrate various statistical methods provided in this chapter. The dataset can be downloaded from website http://www.srbc.net/programs/CBP/nutrientprogram.htm.

Measurement of the top quark mass in the dilepton channel using mT2 at CDF

We present measurements of the top quark mass using the \mT2, a variable related to the transverse mass in events with two missing particles. We use the template method applied to t\tbar dilepton events produced in p\pbar collisions at Fermilab's Tevatron and collected by the CDF detector. From a data sample corresponding to an integrated luminosity of 3.4 \invfb, we select 236 t\tbar candidate events. Using the \mT2 distribution, we measure the top quark mass to be M_{Top} = 168.0^{+4.8}_{-4.0} $\pm$ {2.9} GeV/c^{2}. By combining the \mT2 with the reconstructed top mass distributions based on a neutrino weighting method, we measure M_{top}=169.3 $\pm$ 2.7 $\pm$ 3.2 GeV/c^{2}. This is the first application of the \mT2 variable in a mass measurement at a hadron collider.

Diphenyl sulphoxide complexes of some divalent metal ions*1

Diphenyl sulphoxide (DPSO) complexes of some divalent metal perchlorates and chlorides are prepared The perchlorates of Mn, Co, Ni, Zn and Cd have the general formula [M(DPSO)6](CIO4)2. The Cu(II) complex is found to have the composition [Cu(DPSO)4] (CIO42. The chloro complex having the formula ZnCl2. 2DPSO, CdCl2.DPSO, HgCl2. DPSO and PdCl2. 2 DPSO have also been obtained. Infrared spectra indicate that the DPSO complexes of Mn, Co, Ni, Cu and Zn are oxygen-bonded while those of Cd, Hg and Pd are sulphur-bonded. The magnetic susceptibility and the optical spectral data reveal octahedral coordination for Mn, Co and Ni complexes. From the electronic spectra of Co and NI complexes, the ligand field parameters, Dq and β, are calculated.

Measurement of the top quark mass in the dilepton channel using mT2 at CDF

We present measurements of the top quark mass using the \mT2, a variable related to the transverse mass in events with two missing particles. We use the template method applied to t\tbar dilepton events produced in p\pbar collisions at Fermilab's Tevatron and collected by the CDF detector. From a data sample corresponding to an integrated luminosity of 3.4 \invfb, we select 236 t\tbar candidate events. Using the \mT2 distribution, we measure the top quark mass to be M_{Top} = 168.0^{+4.8}_{-4.0} $\pm$ {2.9} GeV/c^{2}. By combining the \mT2 with the reconstructed top mass distributions based on a neutrino weighting method, we measure M_{top}=169.3 $\pm$ 2.7 $\pm$ 3.2 GeV/c^{2}. This is the first application of the \mT2 variable in a mass measurement at a hadron collider.

Infrared absorption studies on some derivatives of xanthic, dithiocarbamic and trithiocarbonic acids

The infrared absorption spectra of some of the derivatives of xanthic Image dithiocarbamic Image and trithiocarbonic Image acids are studied in the sodium chloride optics region and the bands assigned to group frequencies. The position of C---O---C and C=S bands in the derivatives of xanthic acid has been discussed from theoretical and experimental evidences and it is suggested that the two strong bands around 1200 and 1030 cm−1 are due to the Image group. The bands around 980 and 1050 cm−1 in the derivatives of dithiocarbamic and trithiocarbonic acids respectively have been assigned to C=S group frequencies. These bands shift to lower frequency in the corresponding ionic compounds while the bands around 1030 and 1200 cm−1 in the ionic compounds of xanthic acid shift to higher and lower frequencies respectively.

The change of complete symmetry of the crystals during the phase transitions in ferroelectrics and ferromagnetics

The extension of the superposition principle of the symmetries (P. Curie principle of symmetry) for the case of complete symmetry is given. The enumeration of all crystallographical groups of complete symmetry is presented, the number of elements having complete symmetry for each class of the crystals being indicated. The change of complete symmetry of the crystals under the phase transitions is obtained by superimposing the elements of complete symmetry of polar or axial vectors on the one hand, and the elements of complete symmetry of the crystals on the other. The tables of complete symmetry changes for the cubic, rhombic, monoclinic and triclinic crystals during the ferroelectric and ferromagnetic phase transitions are given.

Future chemistry teachers use of knowledge dimensions and high-order cognitive skills in pre-laboratory concept maps

This poster describes a pilot case study, which aim is to study how future chemistry teachers use knowledge dimensions and high-order cognitive skills (HOCS) in their pre-laboratory concept maps to support chemistry laboratory work. The research data consisted of 168 pre-laboratory concept maps that 29 students constructed as a part of their chemistry laboratory studies. Concept maps were analyzed by using a theory based content analysis through Anderson & Krathwohls' learning taxonomy (2001). This study implicates that novice concept mapper students use all knowledge dimensions and applying, analyzing and evaluating HOCS to support the pre-laboratory work.

Hydrolysis of elemental sulphur in a homogeneous medium

Elemental sulphur dissolved in organic solvents (such as chloroform, carbon tetrachloride and benzene) reacts rapidly and quantitatively, with aqueous alkali at room temperature, when this immiscible liquid mixture is homogenized by the addition of ethyl alcohol. The products of reaction under these experimental conditions are sulphide, thiosulphate and a small quantity of sulphite. A mechanism involving the intermediate formation and decomposition of dihydrogen sulphoxide, HSOH, is suggested for the reaction.

Free convection heat transfer from vertical cylinders part II: Exponential surface temperature variation

Investigation on laminar free convection heat transfer from vertical cylinders and wires having a surface temperature variation of the form TW - T∞ = M emx are presented. As in Part I for power law surface temperature variation, the axisymmetric boundary layer equations of mass, momentum and energy are transformed to more convenient forms and solved numerically. The second approximation refines the results of the first upto a maximum of only 2%. Analysis of the results indicates that cylinders can be classified into the same three categories as in Part I, namely, short cylinders, long cylinders, and wires, heat transfer and fluid flow correlations being developed for each case.

Pylväskäytävien suojassa : Pompejilainen peristyylipuutarha sosioekonomisen edustamisen muotona

Pro gradu -tutkielmani käsittelee pompejilaisessa yksityistalossa ollutta puutarhaa, jota kiertää pylväskäytävä tai useampia. Tätä tilaa kutsutaan peristyylipuutarhaksi. Peristyyli oli tärkeä osa roomalaisen ja siis myös pompejilaisen talon julkista osaa. Se oli avoin vierailijoille, siksi voidaan olettaa, että peristyylipuutarhalla olisi haluttu esittää omaa vaurautta ja sosiaalista asemaa. Työni keskittyy siihen, miten talon asukkaan varallisuus ja sosiaalinen asema näkyvät peristyylipuutarhassa. Tutkin myös, mitä muuta peristyyli viestii omistajastaan. Tutkimukseni liitteenä on lista Pompejin yksityistalojen peristyyleistä ja niiden tiedoista. Niitä vertailemalla analysoin sitä, millainen tila peristyylipuutarha on ollut. Aineistona tutkielmassani ovat konkreettisesti Pompejin yksityistalojen peristyylipuutarhat ja niiden rakenteet sekä arkeologiset löydöt. Peristyylipuutarhoja on 168 kappaletta. Lisäksi seinämaalaukset ja piirtokirjoitukset välittävät tietoa niin peristyylistä kuin sen omistajasta. Tiedot peristyyleistä olen kerännyt tutkimuskirjallisuudesta löytyneistä luetteloista, joissa on tietoa Pompejin taloista ja puutarhoista. Murto-osassa peristyylipuutarhoista olen käynyt ja kerännyt niistä tietoa työhöni. Huomioin antiikin kirjallisen tradition, sen käsitellessä aihettani. Ensimmäisenä käsittelen peristyylipuutarhaa arkkitehtuurin kannalta. Tutkin, mihin peristyyli on sijoitettu pompejilaisessa talossa ja millaisia arkkitehtonisia ratkaisuja tilassa on käytetty. Peristyyli on usein talon ovelta avautuvalla näköakselilla, joka leikkaa läpi talon tärkeimpien julkisten tilojen. Ne ovat atrium eli eteishalli, tablinum eli vastaanottohuone ja peristyylipuutarha. Aina peristyyli ei ole tällä akselilla. Joissain taloissa peristyyli voi olla atriumin tai tablinumin paikalla. Pompejin peristyyleissä on pylväskäytäviä yhdestä neljään. Usein puutarhaosa on erotettu pylväskäytävistä aidalla. Seuraavaksi tutkin peristyylipuutarhasta löytyneitä rakenteita, irtaimistoa, kasveja ja istutuksia. Tarkastelen näiden yleisyyttä ja sitä, mitä ne kertovat peristyylin käyttötarkoituksesta. Puutarhoissa on ollut vesikouruja, kaivoja, altaita, suihkulähteitä, vesisäiliöitä ja niiden suuaukkojen renkaita. Kiinteitä rakennelmia ovat tricliniumit eli oleskelu- ja ruokailuryhmät, kotijumalien pyhäköt, alttarit, nissit ja katokset. Irtaimia löytöjä on peristyyleissä monenlaisia. Yleisimpiä ovat pöydät, aurinkokellot, lamput, amforat ja erilaiset astiat sekä ruukut. Kasveja on huomioitu vähän Pompejin kaivauksissa, mutta peristyylipuutarhoista on löytynyt merkkejä puista ja pensaista sekä säännöllisistä ja epäsäännöllisistä istutuksista. Viimeisenä käsittelen peristyylipuutarhan koristelua, ja minkälaisen kuvan se välittää talon omistajasta. Puutarhoissa oli veistoksia ja seinämaalauksia. Molemmissa käsitellään luontoaiheita, jotka ovat helposti liitettävissä puutarhaan. Suosittuja ovat myös mytologiset aiheet. Veistoskoristelussa selkeästi yleisin on viinin jumala Dionysos ja häneen liittyvät hahmot. Myös muita jumaluuksia esiintyy kuten Venus. Se ja Dionysos liitettiin antiikissa luontoon ja puutarhaan. Peristyylipuutarha oli monipuolinen tila, jossa eri elämänalueet kohtasivat toisensa. Peristyyleissä voitiin työskennellä. Puutarhaosa saattoi olla hyötykäytössä esimerkiksi kasvimaana. Peristyylissä tai sen ympäristössä oleskeltiin, juhlittiin ja viihdytettiin vieraita, siksi siellä esitettiin omaa varakkuutta runsaalla veistoskoristelulla, altailla ja suihkulähteillä. Jo laaja pinta-alainen peristyyli oli osoitus vauraudesta. Aina ei haluttu näyttää varakkuutta, vaan joskus koristeellinen peristyyli oli syrjässä talon ovelta avautuvalta näköakselilta. Uskonto oli osa peristyyliä, vaikka uskonnon harjoittamiseen liittyvät rakenteet sijoitettiin yleensä talon muihin tiloihin. Uskonto ja mytologia ovat kuitenkin vahvasti läsnä peristyylien koristelussa. Selkeitä poliittisia viittauksia peristyylipuutarhoissa on vähän, mutta roomalaisia piirteitä niissä voidaan havaita. Roomalaiset vaikutteet peristyylin koristelussa ja arkkitehtuurissa viestittävät mahdollisesti talon omistajan roomalaismielisyydestä. Roomalaiset piirteet ovat myös olleet trendejä aikakauden peristyyleissä.

Towards Explaining the Use of Control Mechanisms in Foreign Subsidiaries of MNCs (summary section only)

Control is central to management and there is already a considerable body of research on control. However, the emergence and growth of multinational corporations (MNCs) has renewed the interest in control, as MNCs are complex (often large) organizations that face circumstances beyond those of national business organizations. The geographical dispersion of MNC activities means that the headquarters controls subsidiaries that differ with regard to power and that are embedded in different cultural, political, legal and educational systems. Foreign subsidiary control also takes place across language boundaries and physical (i.e. geographical) distances. In face of these challenges, how are foreign subsidiaries controlled? The thesis explores different types of control mechanisms and attempts to explain the degree to which they are used to control foreign subsidiaries. It contributes to existing knowledge on control by exploring how five different control mechanisms are related to each other. Previous research has tended to focus only on one or two control mechanisms and seldom has their effect on each other been explored. The thesis also contributes by including two central aspects of the MNC that have been neglected in much of the research on foreign subsidiary control: language competence of subsidiary staff and physical distance between the headquarters and its subsidiaries. The findings indicate that specific control mechanisms should not be studied in isolation as there are intricate relationships among the different control mechanisms. Language competence of the subsidiary staff can furthermore affect the type and degree of control that the headquarters can exercise over a subsidiary. The findings also indicate that changes in the physical distance between subsidiaries and its headquarters (i.e. a relocation of the headquarters as part of a restructuring process) can have great consequences for the headquarters-subsidiary relationship.

The impact of stock option incentives on investment and firm value

This paper analyzes the relations among firm-level stock option portfolio incentives, investment, and firm value based on a sample of Finnish firms during the time period 1987 – 2000. Utilizing exact and complete information regarding stock option portfolio characteristics, we find some evidence that firm investment is increasing in the incentives to increase stock price (delta) and risk (vega). Furthermore, we find strong evidence of a positive relation between both incentive effects and firm value (Tobin’s Q). In contrast, when we allow for stock option incentives, investment, and firm value to be simultaneously determined, we find no evidence that investment is increasing in incentives. However, even after controlling for endogeneity, we find that both incentive effects arising from stock option compensation display a positive and significant effect on firm value. Finally, in contradiction to earlier findings, we observe that neither Tobin’s Q nor investment drives incentives.

Numerically Exact Study of Polarizabilities and Hyperpolarizabilities of Correlated Conjugated Organic Models

Polarizabilities and Hyperpolarizabilities of conjugated organic chains are calculated using correlated model Hamiltonians. While correlations reduce the Polarizabilities and extend the range of linear response, the Hyperpolarizabilities essentially are unaffected by the same. This explains the apparently large Hyperpolarizabilities of conjugated electronic systems.