Fabrication and characterization of a thermal switch

The development of a thermal switch based on arrays of liquid–metal micro-droplets is presented. Prototype thermal switches are assembled from a silicon substrate on which is deposited an array of 1600 30-μm liquid–metal micro-droplets. The liquid–metal micro-droplet array makes and breaks contact with a second bare silicon substrate. A gap between the two silicon substrates is filled with either air at 760 Torr, air at of 0.5 Torr or xenon at 760 Torr. Heat transfer and thermal resistance across the thermal switches are measured for “on” (make contact) and “off” (break contact) conditions using guard-heated calorimetry. The figure of merit for a thermal switch, the ratio of “off” state thermal resistance over “on” state thermal resistance, R_off/R_on, is 129 ± 43 for a xenon-filled thermal switch that opens 100 μm and 60 ± 17 for an 0.5 Torr air-filled thermal switch that opens 25 μm. These thermal resistance ratios are shown to be markedly higher than values of R_off/R_on for a thermal switch based on contact between polished silicon surfaces. Transient temperature measurements for the liquid–metal micro-droplet switches indicate thermal switching times of less than 100 ms. Switch lifetimes are found to exceed one-million cycles.     

Assessment of grape yield and composition using the reflectance based Water Index in Mediterranean rainfed vineyards

In rainfed vineyards water deficits play a major role in determining berry yield and composition. Therefore, reliable indicators of vine water status might be of great value for the optimization of grape yield and quality. In the present study the feasibility of using hyperspectral reflectance indices related to plant biophysical properties at predicting berry yield and quality attributes in rainfed vineyards is assessed. The study was conducted on Vitis vinifera cv. Chardonnay in commercial vineyards in the D.O. Penedès region (Catalonia, Spain) over two consecutive years (2007–2008). Field measurements of fractional intercepted Photosynthetic Active Radiation (fIPAR), canopy reflectance, predawn water potential (Ψ_p) and the canopy to air temperature difference at midday (ΔT_midday) were conducted at the stage of veraison. Yield, Total Soluble Solids (TSS), Titratable Acidity (TA) and the ratio TSS/TA (maturation index, IMAD) were determined at harvest. Contrasted water availability among vineyards prompted considerable variation in berry yield and quality attributes. Across years, higher yield was accompanied by higher TA (r = 0.59, p < 0.01) and lower IMAD (r = ? 0.63, p < 0.01) while no significant relationship was observed between yield and TSS. Yield was related to canopy vigor (fIPAR) in a variable extend: in 2007, yield was positively related to fIPAR (r = 0.71, p < 0.05) while yield was found to decrease along with increasing fIPAR in 2008 (r = ? 0.62, p < 0.05). Contrastingly, NDVI provided consistent estimates of yield across years (r = 0.57, p < 0.05). These results suggest that NDVI might be more appropriate to characterize the effects of varying water availability on yield than fIPAR. In addition, yield was found to be related to ΔT_midday (r = ? 0.63 and r = ? 0.66, in 2007 and 2008, respectively). Accordingly, the Water Index (WI), an indicator of vine water status, provided robust estimates of yield across years (r = 0.61, p < 0.01). The strength of the correlation between NDVI and WI vs. yield suggests that yield was influenced by changes in both leaf area (intercepted light) and photosynthesis (stomatal aperture) in a variable extent according to the timing and severity of water deficits in the years of study. Berry quality attributes did not show significant relationships against fIPAR but were related to ΔT_midday. Accordingly, NDVI did not show significant correlation with berry quality attributes, while WI was found to be consistently related to TA (r = 0.70, p < 0.01) and IMAD (r = ? 0.71, p < 0.01) across years. The results obtained suggest that the WI might provide reliable estimates of berry quality attributes in vineyards experiencing moderate to severe water deficits with potential application in precision viticulture activities such as selective harvesting according to grape quality attributes as well as for ripening assessment.     

Tyrolean termination tool: Techniques and features

The Tyrolean Termination Tool (T_TT for short) is a powerful tool for automatically proving termination of rewrite systems. It incorporates several new refinements of the dependency pair method that are easy to implement, increase the power of the method, result in simpler termination proofs, and make the method more efficient. T_TT employs polynomial interpretations with negative coefficients, like x − 1 for a unary function symbol or x − y for a binary function symbol, which are useful for extending the class of rewrite systems that can be proved terminating automatically. Besides a detailed account of these techniques, we describe the convenient web interface of T_TT and provide some implementation details.     

Fabrication and characterization of Pb-free transparent dielectric layer for plasma display panel

Glasses within the Bi₂O₃–B₂O₃–BaO–ZnO system were examined as potential replacements for PbO-based glass frits with low firing temperatures. These frits are used in the transparent dielectric layer of plasma display panels (PDP). The glass transition temperature (T_g) of the prepared glasses varied between 450 and 460 °C. These glasses display dynamic dielectric properties, high transparency and thermal expansion as well as matching well with substrate glass. The thermal coefficient of expansion (TCE) was with the desired range of 81–86×10⁻⁷/K. Moreover, when the screen printed film was heat-treated at 570 °C for 30 min, optical transmittance (83%), root-mean square (rms) roughness (177.6 Å), dielectric constant (10.25) and withstand voltage (4.15 kV) satisfied the requirements necessary for transparent dielectric layers to be used in PDP applications.     

Dielectric and piezoelectric properties of [0 0 1] and [0 1 1]-poled relaxor ferroelectric PZN–PT and PMN–PT single crystals

The properties of PZN–PT and PMN–PT single crystals of varying compositions and orientations have been investigated. Among the various compositions studied, [0 0 1]-optimally poled PZN-(6–7)%PT and PMN-30%PT exhibit superior dielectric and piezoelectric properties, with K^T ≈ 6800–8000, d₃₃ ≈ 2800 pC/N, d₃₁ ≈ −(1200–1800) pC/N for PZN-(6–7)%PT; and K^T = 7500–9000, d₃₃ = 2200–2500 pC/N and d₃₁ = −(1100–1400) pC/N for PMN-30%PT. These two compositions are also fairly resistant to over-poling. The [0 0 1]-poled electromechanical coupling factors (k₃₃, k₃₁ and k_t) are relatively insensitive to crystal composition. [0 1 1]-optimally poled PZN-7%PT single crystal also exhibits extremely high d₃₁ values of up to −4000 pC/N with k₃₁ ≈ 0.90–0.96. While [0 1 1]-poled PZN-7%PT single crystal becomes over-poled with much degraded properties when poled at and above 0.6 kV/mm, PZN-6%PT crystal shows no signs of over-poling even when poled to 2.0 kV/mm. The presence of a certain amount (i.e., 10–15%) of orthorhombic phase in a rhombohedral matrix has been found to be responsible for the superior transverse piezoelectric properties of [0 1 1]-optimally poled PZN-(6–7)%PT. The present work shows that flux-grown PZN–PT crystals exhibit superior and consistent properties and improved over-poling resistance to flux-grown PMN–PT crystals and that, for or a given crystal composition, flux-grown PMN–PT crystals exhibit superior over-poling resistance to their melt-grown counterparts.     

Rule-based Mamdani-type fuzzy modelling of thermal performance of multi-layer precast concrete panels used in residential buildings in Turkey

Heat insulation applied on outer wall surfaces of buildings for the purpose of conserving energy, can be analyzed experimentally, mathematically and by using simulation modelling. In this study, simulation modelling of insulation layer (d₂), for residential buildings in 81 cities classified into four climatic regions in Turkey was investigated. This stimulus model is constructed into rule-based Mamdani-type fuzzy modelling (RBMTF), using input parameters (U_w, T_e) and output parameter d₂, described by RBMTF if-then rules. RBMTF has been designed using the MATLAB 7.04 fuzzy logic toolbox. The d₂ was predicted using two input parameters: U_w and T_e. The values for U_w ranged from 0.4 to 0.7. The values for T_e ranged from ?43 °C to ?3 °C. The values for d₂ ranged from 0.07 to 0.21. Seven linguistic terms were considered for each of the input and output variables, namely Very Low (L1), Low (L2), Negative Medium (L3), Medium (L4), Positive Medium (L5), High (L6), Very High (L7). R² for the testing data were about 97.4%. Overall, RBMTF can be used as a reliable modelling method for thermal performance of multi-layer precast concrete panels used in residential buildings’ studies.     

Particle behavior in a vertical channel with thermal convection in the low Grashof number regime

In the present study the motion of isothermal circular particles in a two-dimensional vertical channel with hot and cold isothermal conditions at the left and right walls in the presence of thermal convection was investigated. An isothermal circular particle for a particle to fluid density ratio ρ_r = ρ_p/ρ_f = of 1.00232 where ρ_p and ρ_f denote the particle and the fluid densities, respectively, was considered. Numerical simulations were carried out using the direct forcing/fictitious domain (DF/FD) method to investigate the solid motion in a fluid with a Prandtl number of 0.7 for different Grashof numbers ranging from 0 to 50. Under the conditions of the present problem, the particle motion is mainly governed by the thermal convection between the side walls of the channel and the particle, and by the wall confinement. The results of the present study indicate that three regimes of particle behavior can be identified in the present range of Grashof numbers regardless of the cold and hot thermal boundary conditions of the particle. In the first regime, the particle exhibits steady settling behavior; in the second regime, it undergoes a transient overshoot before the steady settling; in the third regime, the particle motion is submerged in the thermal levitation.     

Extension of a hybrid thermal LBE scheme for large-eddy simulations of turbulent convective flows

Following the work of Lallemand and Luo [Lallemand P, Luo L-S. Theory of the lattice Boltzmann method: acoustic and thermal properties in two and three dimensions. Phys Rev E 2003;68:036706] we validate, apply and extend the hybrid thermal lattice Boltzmann scheme (HTLBE) by a large-eddy approach to simulate turbulent convective flows. For the mass and momentum equations, a multiple-relaxation-time LBE scheme is used while the heat equation is solved numerically by a finite difference scheme. We extend the hybrid model by a Smagorinsky subgrid scale model for both the fluid flow and the heat flux. Validation studies are presented for laminar and turbulent natural convection in a cavity at various Rayleigh numbers up to 5 × 10¹⁰ for Pr = 0.71 using a serial code in 2D and a parallel code in 3D, respectively. Correlations of the Nusselt number are discussed and compared to benchmark data. As an application we simulated forced convection in a building with inner courtyard at Re = 50 000.     

Improvements of conductive property and room temperature magnetoresistance in Ag–Ti-added La0.67Ba0.33MnO3

Structural, magnetic, electrical, and magnetotransport properties have been carried out on the Ag-added La_0.67Ba_0.33MnO₃/(TiO₂)_0.035 (LBT) (abbreviated by LBT/Ag_x,) composites. Ag addition has little influence on the magnetization or Curie temperature (T_C), but decreases the resistivity (ρ) and sharps the ρ peak evidently. The ρ in the ferromagnetic (FM) metallic regime is proportional to T², reflecting that the conductive mechanism mainly arises from the electron–electron scattering. In the paramagnetic (PM) insulating region, the ρ data fit well to the self-trapped small polaron hopping model. The ρ–T curves for x = 0.27 and 0.30 samples fit well with the phenomenological percolation approach, which is based on the phases segregation of ferromagnetic metallic clusters and paramagnetic insulating regions. These excellent agreements highlight the dominant intrinsic behavior of LBT. In addition, from the magnetotransport measurements, a large magnetoresistance (MR) ratio up to 41% was obtained at 280 K, and 10 kOe for x = 0.27 sample. The good fits between the field dependence of MR and Brillouin function indicate that the MR behavior in the Ag-added LBT is induced by the spin-dependent hopping of the electrons among the spin clusters, and which is related to the increase and growth of the FM spin clusters.     

Remote sensing of canopy light use efficiency in temperate and boreal forests of North America using MODIS imagery

Light use efficiency (LUE) is an important variable characterizing plant eco-physiological functions and refers to the efficiency at which absorbed solar radiation is converted into photosynthates. The estimation of LUE at regional to global scales would be a significant advantage for global carbon cycle research. Traditional methods for canopy level LUE determination require meteorological inputs which cannot be easily obtained by remote sensing. Here we propose a new algorithm that incorporates the enhanced vegetation index (EVI) and a modified form of land surface temperature (T_m) for the estimation of monthly forest LUE based on Moderate Resolution Imaging Spectroradiometer (MODIS) imagery. Results demonstrate that a model based on EVI × T_m parameterized from ten forest sites can provide reasonable estimates of monthly LUE for temperate and boreal forest ecosystems in North America with an R² of 0.51 (p < 0.001) for the overall dataset. The regression coefficients (a, b) of the LUE–EVI × T_m correlation for these ten sites have been found to be closely correlated with the average EVI (EVI_ave, R² = 0.68, p = 0.003) and the minimum land surface temperature (LST_min, R² = 0.81, p = 0.009), providing a possible approach for model calibration. The calibrated model shows comparably good estimates of LUE for another ten independent forest ecosystems with an overall root mean square error (RMSE) of 0.055 g C per mol photosynthetically active radiation. These results are especially important for the evergreen species due to their limited variability in canopy greenness. The usefulness of this new LUE algorithm is further validated for the estimation of gross primary production (GPP) at these sites with an RMSE of 37.6 g C m^? 2 month^? 1 for all observations, which reflects a 28% improvement over the standard MODIS GPP products. These analyses should be helpful in the further development of ecosystem remote sensing methods and improving our understanding of the responses of various ecosystems to climate change.     

The B-rich side of the B–C phase diagram

The melting behavior of ß-boron at the boron-rich side of the B–C binary phase diagram is a long standing question whether eutectic or peritectic. Floating zone experiments have been employed to determine the melting type on a series of C-containing feed-rods prepared by powder metallurgy and sinter techniques. Melting point data as a function of carbon-content clearly yielded a peritectic reaction isotherm: L+B_4+δC=(ßB). The partition coefficient of carbon is ~2.6. The experimental melting point data were used to improve the existing thermodynamic modeling of the system B–C. Relative to the thermodynamically accepted melting point of pure ßB (T_M=2075 °C), the calculated reaction isotherm is determined at 2100.6 °C, a peritectic point at 0.75 at% C and a maximum solid solubility of 1.43 at% C in (ßB) at reaction temperature. With the new melting data the refractory system Hf–B–C has been recalculated and the liquidus surface is presented. The influence of the melting behavior of (ßB) on the phase reactions in the B-rich corner of M–B–C diagrams will be discussed and demonstrated in case of the Ti–B–C system.     

Scalable 2D Convex Hull and Triangulation Algorithms for Coarse Grained Multicomputers

In this paper we describe scalable parallel algorithms for building the convex hull and a triangulation ofncoplanar points. These algorithms are designed for thecoarse grained multicomputermodel:pprocessors withO(n/p)⪢O(1) local memory each, connected to some arbitrary interconnection network. They scale over a large range of values ofnandp, assuming only thatn⩾p^1+ε(ε>0) and require timeO((T_sequential/p)+T_s(n, p)), whereT_s(n, p) refers to the time of a global sort ofndata on approcessor machine. Furthermore, they involve only a constant number of global communication rounds. Since computing either 2D convex hull or triangulation requires timeT_sequential=Θ(n log n) these algorithms either run in optimal time,Θ((n log n)/p), or in sort time,T_s(n, p), for the interconnection network in question. These results become optimal whenT_sequential/pdominatesT_s(n, p) or for interconnection networks like the mesh for which optimal sorting algorithms exist.     

Internet use and verbal aggression: The moderating role of parents and peers

This research investigated the influence of parent–adolescent communication quality, as perceived by the adolescents, on the relationship between adolescents’ Internet use and verbal aggression. Adolescents (N = 363, age range 10–16, M_T1 = 12.84, SD = 1.93) were examined twice with a six-month delay. Controlling for social support in general terms, moderated regression analyses showed that Internet-related communication quality with parents determined whether Internet use is associated with an increase or a decrease in adolescents’ verbal aggression scores over time. A three way interaction indicated that high Internet-related communication quality with peers can have disadvantageous effects if the communication quality with parents is low. Implications on resources and risk factors related to the effects of Internet use are discussed.     

The possibility of using C20 fullerene and graphene as semiconductor segments for detection,and destruction of cyanogen-chloride chemical agent

Detection of hazardous chemical species by changing the electrical conductivity of a semiconductor matter is a proposed and applied way for decreasing their subsequent unpleasant effects. Recently, many examples of using inorganic or organic materials, polymeric, and also nano-sized species as sensors were reported in which, in some cases, those matters were strongly affective and suitable.In this project, we have made an assessment on whether the graphene segment or C₂₀ fullerene, able to sense the existence of cyanogen chloride NCCl? In order to gain trustable results, the possible reaction pathways along with the adsorption kinetics were investigated. Moreover, the electronic density of states DOS showed that C₂₀ fullerene senses the existence of cyanogen chloride agent with a clearer signal (ΔE_g = 0.0110 eV) compared to the graphene segment (ΔE_g = 0.0001 eV). Also the adsorption energy calculations showed that cyanogen chloride could be adsorbed by the fullerene in a multi-step process (E_ads1 = −0.852 kcal mol⁻¹; E_ads2 = −0.446 kcal mol⁻¹; E_ads3 = −2.330 kcal mol⁻¹).     

Deadline-based scheduling in support of real-time data delivery

The use of deadline-based scheduling in support of real-time delivery of application data units (ADUs) in a packet-switched network is investigated. Of interest is priority scheduling where a packet with a smaller ratio of T/H (time until delivery deadline over number of hops remaining) is given a higher priority. We refer to this scheduling algorithm as the T/H algorithm. T/H has time complexity of O(log N) for a backlog of N packets and was shown to achieve good performance in terms of the percentage of ADUs that are delivered on-time. We develop a new and efficient algorithm, called T/H − p, that has O(1) time complexity. The performance difference of T/H, T/H − p and FCFS are evaluated by simulation. Implementations of T/H and T/H − p in high-speed routers are also discussed. We show through simulation that T/H − p is superior to FCFS but not as good as T/H. In view of the constant time complexity, T/H − p is a good candidate for high-speed routers when both performance and implementation cost are taken into consideration.     

Measurement and thermodynamic model study on equilibrium solubility in the aqueous system of magnesium chloride and magnesium bromide

Solubilities of the ternary system MgCl₂–MgBr₂–H₂O at T=(288.15, 308.15, 323.15 and 333.15) K were investigated, and the crystallization behaviour of solid solution Mg(Cl,Br)₂·6H₂O was established. Combining our experimental results with other experimental data available in the literature at T=(298.15 and 313.15) K, the pure electrolyte solution parameters for binary systems, the T-variation mixing parameters θ_Cl,Br and ψ_Mg,Cl,Br and the equilibrium constants equations of the solid solution were obtained. Based on Pitzer model and Harvie–Weare solubility approach, the solubility modelling approach achieved a very good agreement with chloride and bromide salts equilibrium solubility data. Temperature-dependent equation in the system provides reasonable mineral solubility at T=(288.15–333.15)  K. This model expands the solubility calculation in the systems containing solid solution by evaluating chloride–bromide mixing solution parameters. Limitations of the mixed solution models due to data insufficiencies are discussed.     

Stereoelectronic interaction effects on the conformational properties of hydrogen peroxide and its analogues containing S and Se atoms: An ab initio,hybrid-DFT study and NBO analysis

Ab initio molecular orbital (MP2/6-311+G**//MP2/6-31G+G**) and hybrid-density functional theory (B3LYP/6-311+G**//MP2/6-311+G**) methods and NBO analysis were used to study the stereoelectronic interaction effects on the conformational properties of hydrogen peroxide (1), hydrogen disulfide (2) and hydrogen diselenide (3). The results showed that the Gibbs free energy difference (G_T − G_S) values at 298.15 K and 1 atm between the skew (S) and trans (T) conformations (ΔG_T–S) increase from compound 1 to compound 2 but decrease from compound 2 to compound 3. The C conformations of compounds 1–3 are less stable than their S and T conformations. Based on these results, the racemization processes of the axial symmetrical (C₂ symmetry) conformations of compounds 1–3 take place via their T conformations. Based on the optimized ground state geometries using the MP2/6-311+G** level of theory, the NBO analysis of donor–acceptor (bond–antibond) interactions revealed that the stabilization (resonance) energy associated with LP₂M2 → σ*_M3-H4 electronic delocalization for the S conformations of compounds 1–3 are 1.35, 5.94 and 4.68 kcal mol⁻¹, respectively. There is excellent agreement between the variations of the calculated ΔG_T–S and stabilization (resonance) energies associated with LP₂M2→σ*_M3-H4 electronic delocalization for the S conformations of compounds 1–3. The correlations between resonance energies, orbital integrals, dipole moments, bond orders, structural parameters and conformational behaviors of compounds 1–3 have been investigated. Test were made of complete basis set methods (CBS-QB3, CBS-4 and CBS-Q), the first two gave results essentially indistinguishable from those we used, but the CBS-Q results were in disagreement with experimental and other theoretical results.     

On reliability of the folded hypercubes

In this paper, we explore the 2-extra connectivity and 2-extra-edge-connectivity of the folded hypercube FQ_n. We show that κ₂(FQ_n) = 3n − 2 for n ⩾ 8; and λ₂(FQ_n) = 3n − 1 for n ⩾ 5. That is, for n ⩾ 8 (resp. n ⩾ 5), at least 3n − 2 vertices (resp. 3n − 1 edges) of FQ_n are removed to get a disconnected graph that contains no isolated vertices (resp. edges). When the folded hypercube is used to model the topological structure of a large-scale parallel processing system, these results can provide more accurate measurements for reliability and fault tolerance of the system.     

Mechanism and kinetic study of 3-fluoropropene with hydroxyl radical reaction

Potential energy surface for the reaction of hydroxyl radical (OH) with 3-fluoropropene (CH₂CHCH₂F) has been studied to evaluate the reaction mechanisms, possible products and rate constants. It has been shown that the CH₂CHCH₂F with OH reaction takes place via a barrierless addition/elimination and hydrogen abstraction mechanism. It is revealed for the first time that the initial step for the barrierless additional process involves a pre-reactive loosely bound complex (CR1) that is 1.60 kcal/mol below the energy of the reactants. Subsequently, the reaction bifurcates into two different pathways to form IM1 (CH₂CHOHCH₂F) and IM2 (CH₂OHCHCH₂F), which can decompose or isomerize to various products via complicated mechanisms. Variational transition state model and multichannel RRKM theory are employed to calculate the temperature-, pressure-dependent rate constants and branching ratios. At atmospheric pressure with He as bath gas, IM1 formed by collisional stabilization is dominated at T ≤ 600 K; whereas the direct hydrogen abstraction leading to CH₂CHCHF and H₂O are the major products at temperatures between 600 and 3000 K, with estimated contribution of 72.9% at 1000 K. Furthermore, the predicted rate constants are in good agreement with the available experimental values.     

Thermodynamic reassessment of the novel solid-state thermal energy storage materials: Ternary polyalcohol and amine system pentaglycerine-tris(hydroxymethyl)-amino-methane-neopentylglycol (PG-TRIS-NPG)

Organic polyalcohol and amine globular molecular crystals such as PG, TRIS, and NPG are considered as the most promising potential candidates for solid-state thermal energy storage in the orientationally disordered high temperature phases. In this study, we first propose a new PG-TRIS-NPG phase diagram based on experimental data of the three sub-binary systems NPG-PG, PG-TRIS, and NPG-TRIS with CALPHAD methodology. The NPG-PG binary phase diagram was optimized using sub-regular models that showed complete miscibility in the entire compositional range of high temperature γ′ (FCC) phase region, and an invariant equilibrium point at 299.5 K. The NPG-TRIS binary system was also calculated using sub-regular model, from sub-ambient to well above the melting temperatures, and determined three invariant equilibria at 311.1 K, 391.8 K, and 410.6 K, respectively. These calculated binary phase diagrams are in good agreement with the experimental data. The PG-TRIS-NPG ternary system has also been calculated and qualitatively analyzed using the CALPHAD method and Thermo-Calc software. A set of self-consistent thermodynamic parameters formulating the Gibbs energies of various phase in the PG-TIRS-NPG ternary system are obtained in the present work. Thermodynamic properties such as several isotherms, isopleths, and liquidus projections are calculated by using present datasets as shown in this work in which the solid ternary compound (TRIS_0.5NPG_0.5)_XPG_1−X (0.1≤x≤0.9), (TRIS_0.5PG_0.5)_XNPG_1−X (0.1≤x≤0.9), and (PG_0.5NPG_0.5)_XTRIS_1−X (0.1≤x≤0.9) with various solid-solid phase transitions at different temperatures could apply to applications in the solid-state thermal energy storage.