Investment timing and optimal capacity choice for small hydropower projects

This paper presents a method for assessing small hydropower projects that are subject to uncertain electricity prices. We present a real options-based method with continuous scaling, and we find that there is a unique price limit for initiating the project. If the current electricity price is below this limit it is never optimal to invest, but above this limit investment is made according to the function for optimal size. The connection between the real option and the physical properties of a small hydropower plant is dealt with using a spreadsheet model that performs a technical simulation of the production in a plant, based on all the important choices for such a plant. The main results of the spreadsheet are simulated production size and the investment costs, which are in turn used for finding the value of the real option and the price limit. The method is illustrated on three different Norwegian small hydropower projects.     

Disjoint hamiltonian cycles in bipartite graphs

Let G=(X,Y) be a bipartite graph and define . Moon and Moser [J. Moon, L. Moser, On Hamiltonian bipartite graphs, Israel J. Math. 1 (1963) 163-165. MR 28 # 4540] showed that if G is a bipartite graph on 2n vertices such that , then G is hamiltonian, sharpening a classical result of Ore [O. Ore, A note on Hamilton circuits, Amer. Math. Monthly 67 (1960) 55] for bipartite graphs. Here we prove that if G is a bipartite graph on 2n vertices such that , then G contains k edge-disjoint hamiltonian cycles. This extends the result of Moon and Moser and a result of R. Faudree et al. [R. Faudree, C. Rousseau, R. Schelp, Edge-disjoint Hamiltonian cycles, Graph Theory Appl. Algorithms Comput. Sci. (1984) 231-249].     

Centrifugal distortion effects in the hyperfine spectrum of KCl

The hyperfine spectrum of KCl has been examined at near-zero electric field and zero magnetic field using a molecular beam electric resonance spectrometer. Rotational as well as vibrational shifts have been observed in both nuclear quadrupole interactions. With $\text{eqQ = Q}{}_{00}\text{+ Q}{}_{10}\text{(v +}\text{1}\text{2}\text{) + Q}{}_{20}\text{(v +}\text{1}\text{2}\text{)}{}^2\text{+ Q}{}_{01}\text{J(J + 1)}$, we find (all in units of kHz) for K in ³⁹K³⁵Cl: Q₀₀ = ?5691.47 ± 0.04, Q₁₀ = 51.32 ± 0.06, Q₂₀ = ?0.205 ± 0.020, Q₀₁ = 0.014 ± 0.007, Q₀₀(K³⁷Cl) ? Q₀₀(K³⁵Cl) = ?0.03 ± 0.07; for Cl in ³⁹K³⁵Cl: Q₀₀ = 137.0 ± 0.3, Q₁₀ = ?163.2 ± 0.5, Q₂₀ = 1.57 ± 0.15, Q₀₁ = 0.07 ± 0.03, $\text{[}\text{Q(}{}^{35}\text{Cl}\text{)}\text{Q(}{}^{37}\text{Cl}\text{)}\text{]Q}{}_{00}\text{(}\text{K}{}^{37}\text{Cl}\text{) ? Q}{}_{00}\text{(}\text{K}{}^{35}\text{Cl}\text{) = ?0.5 ± 0.6}$; and magnetic constants c_K = 0.154 ± 0.007, c_Cl = 0.435 ± 0.010, c₃ = 0.035 ± 0.012, and c₄ = 0.009 ± 0.006. These have been used to provide a mapping of the field gradients at both nuclear sites to fourth order in $\text{ξ =}\text{(r ? r}{}_{\mathrm{e}}\text{)}\text{r}{}_{\mathrm{e}}$. We find eQq_K(ξ) = (?5692.5 ± 2.5) + (1.7 ± 0.8) × 10⁴ξ + (?2. ± 4.) × 10⁴ξ² + (?8. ± 18.) × 10⁵ξ³ + (8. ± 15.) × 10⁶ξ⁴ and eQq_Cl(ξ) = (120. ± 22.) + (8. ± 4.) × 10⁴ξ + (?5.8 ± 2.0) × 10⁵ξ² + (?1.1 ± 1.6) × 10⁷ξ³ + (1.1 ± 1.3) × 10⁸ξ⁴.     

Angle-resolved photoemission from Fe(110): Determination of E()

Using angle-resolved photoemission spectroscopy utilizing polarized synchrotron radiation with a clean Fe(110) sample, we identified each of the Σ₁-, Σ₃- and Σ₄-band peaks with certainty using symmetry selection rules. We also determined energy band dispersion along the γ-Σ-N direction in the bulk Brillouin zone assuming direct transitions. There are small discrepancies between the observed bands and recent ground-state band calculations possibly due to Coulomb correlation effects. A surface state with odd symmetry about the [001] crystal direction and a binding energy of 0.15 eV at γ in the surface Brillouin zone was observed. Our results show that the ground-state calculations of ferromagnetic iron based on the local exchange correlation potential are basically in agreement with experimental dispersion relationship measurements.     

Modification of Wyoming montmorillonite surfaces using a cationic surfactant

Surfaces of Wyoming SWy-2-Na-montmorillonite were modified using ultrasonic and hydrothermal methods through the intercalation and adsorption of the cationic surfactant octadecyltrimethylammonium bromide (ODTMA). Changes in the surfaces and structure were characterized using X-ray diffraction (XRD), thermal analysis (TG), and electron microscopy. The ultrasonic preparation method results in a higher surfactant concentration within the montmorillonite interlayer when compared with that from the hydrothermal method. Three different molecular environments for surfactants within the surface-modified montmorillonite are proposed upon the basis of their different decomposition temperatures. Both XRD patterns and TEM images demonstrate that SWy-2-Na-montmorillonite contains superlayers. TEM images of organoclays prepared at high surfactant concentrations show alternate basal spacings between neighboring layers. SEM images show that modification with surfactant reduces the clay particle size and aggregation. Organoclays prepared at low surfactant concentration display curved flakes, whereas they become flat with increasing intercalated surfactant. Novel surfactant-modified montmorillonite results in the formation of new nanophases with the potential for the removal of organic impurities from aqueous media.     

Bacteriochlorophyll e monomers,but not aggregates,sensitize singlet oxygen: implications for a self-photoprotection mechanism in chlorosomes

Sensitization of singlet delta oxygen (O2(1delta(g))) by bacteriochlorophyll e (BChle) has been investigated to gain a better understanding of the photoprotection mechanism(s) operating in chlorosomes of green photosynthetic bacteria. The sensitization process has been studied in media where BChle forms monomers (acetone and aqueous solutions containing 0.5% Triton X-100 [TX]) and in systems where BChle aggregates, namely, aqueous solutions containing 0.003% monogalactosyl diglyceride (MGDG) and chlorosomes(control as well as hexanol perturbed) from Chlorobium phaeobacteroides strain CL1401. In Ar-purged acetone, BChle triplets (BChle triplets) have a lifetime of a few tens of microseconds; however, in air-saturated acetone, quenching of BChle triplets by ground-state oxygen (O2(3sigma(-)g)) and formation of O2(1delta(g)) take place. The O2(1delta(g)) so formed is susceptible to quenching by BChle0, a ground-state BChle molecule. A Stern-Volmer analysis reveals a linear fit between the decay rate of O2(1delta(g)) and the BChle concentration. The rate constants for the quenching of O2(1delta(g)) by BChle0 and for the deactivation of O2(1delta(g)) by the solvent come out to be kq = (1.4 +/- 0.1) x 10(9) M(-1) s(-1) and k0 = (18.5 +/- 0.7) x 10(3) s(-1), respectively. The absolute quantum yield of O2(1delta(g)) sensitization by BChle monomers is 0.65 +/- 0.15 in air-saturated acetone. In aqueous phase, the triplet lifetime of BChle aggregates in native or hexanol-perturbed chlorosomes shortens by more than two orders of magnitude when compared with the triplet lifetime of BChle monomers in 0.5% TX solution (a few hundreds of microseconds). Quenching by carotenoids (Car) makes only a minor contribution to the decay of BChle triplets in aggregates. Because O2(1delta(g)) sensitization by BChle triplets could be detected neither in MGDG aggregates nor in chlorosomes (control as well as hexanol perturbed), it is concluded that (1) this process is highly likely when BChle is present as a monomer but not when it is tightly packed in artificial aggregates or in chlorosomes; and (2) Car, though vital for the baseplate BChla, are dispensable for BChle.     

Preparation of sub-micrometer silica shells using poly(1-methylpyrrol-2-ylsquaraine)

Poly(1-methylpyrrol-2-ylsquaraine) precipitates from reaction solution as uniformly spherical particles with a diameter of 1.3 microm. Upon heating, the particles reduce in diameter until extinction at approximately 630 degrees C. Treatment of the particles with 9:1 tetraethoxysilane:ethanol solution, and subsequent hydrolysis in dilute acid, results in a polymer core-silica shell structure. Removal of the core, upon heating to 660 degrees C, results in an amorphous silica shell with a diameter half that of the initial template sphere. It has been found that the silica shells produced by this method are able to encapsulate organic dyes upon soaking of the shells in chloroform solutions of the dyes, and further washings with fresh chloroform did not remove the dyes. The production of crystalline titanium dioxide shells was also achieved through the use of the polysquaraine particles as a spherical template.     

Partial spread and vectorial generalized bent functions

In 2007, Sun et al. (IEEE Trans Inf Theory 53(8):2922–2933, 2007) presented new variants of RSA, called Dual RSA, whose key generation algorithm outputs two distinct RSA moduli having the same public and private exponents, with an advantage of reducing storage requirements for keys. These variants can be used in some applications like blind signatures and authentication/secrecy. In this paper, we give an improved analysis on Dual RSA and obtain that when the private exponent is smaller than \(N^{0.368}\), the Dual RSA can be broken, where N is an integer with the same bitlength as the modulus of Dual RSA. The point of our work is based on the observation that we can split the private exponent into two much smaller unknown variables and solve a related modular equation on the two unknown variables and other auxiliary variables by making use of lattice based methods. Moreover, we extend this method to analyze the common private exponent RSA scheme, a variant of Dual RSA, and obtain a better bound than previous analyses. While our analyses cannot be proven to work in general, since we rely on some unproven assumptions, our experimental results have shown they work in practice.