Using analysis to influence strategic-decision making: option valuation at ECGD

This case-oriented paper shows how an in-house OR group in a small Government Department (ECGD) influences decision-making by feeding technical analysis directly into strategic decision-making. It covers both the technical detail of the analysis and the OR process which led to implementation. The technical part of the paper describes how the forecast expected cost of giving a fixed interest rate hold to a borrower was estimated using an option valuation. The cost estimation is complicated by the context: ECGD is also providing a guarantee of loan repayment by the overseas borrower to a bank, and ECGD costs include a binary bank margin cost which depends on whether the fixed interest rate hold is taken up by the borrower. The remainder of the paper describes the way OR analysts worked with decision-makers and considers the implications for effective practice.     

Atmospheric chemistry of cyclohexanone: UV spectrum and kinetics of reaction with chlorine atoms

Absolute and relative rate techniques were used to study the reactivity of Cl atoms with cyclohexanone in 6 Torr of argon or 800–950 Torr of N₂ at 295 ± 2 K. The absolute rate experiments gave k(Cl + cyclohexanone) = (1.88 ± 0.38) × 10^?10, whereas the relative rate experiments gave k(Cl + cyclohexanone) = (1.66 ± 0.26) × 10^?10 cm³ molecule^?1 s^?1. Cyclohexanone has a broad UV absorption band with a maximum cross section of (4.0 ± 0.3) × 10^?20 cm² molecule^?1 near 285 nm. The results are discussed with respect to the literature data. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 223–229, 2008     

Epoxy-based electroactive polymer gels

We describe a new type of electroactive polymer gel. In contrast to cross-linked polyacrylates, this system is based on triepoxides cross-linked with polyfunctional amines. The stoichiometry is selected to form a cross-linked gel with excess amino hydrogens. In acid solutions these become cationic and the ionic interactions cause the gel to swell. We describe the mechanical properties of the gels, their response to changes in pH and to electrical activation. The response time is in rough agreement with what would be expected for a diffusional process through a gel of this size (about 100 μm). Samples of smaller dimensions would be expected to respond more rapidly.     

Effects of inlet conditions and surface roughness on the performance of transitions between square and rectangular ducts of the same cross-sectional area

A study has been made of the effects of inlet conditions and surface roughness on the performance of transitions between square and rectangular ducts of the same cross-sectional area. The conditions at entry were varied by using different approach lengths of straight duct and by means of a square screen of woven wire cloth. The surface roughening was accomplished by coating the surface of the transition with graded waterproof silicon carbide paper, whose surface roughness was measured with a Talysurf 4 instrument. All tests were run at Reynolds number 10⁵.

The results indicate that the static pressure loss coefficient significantly increases as the inlet boundary layer thickness increases. This variation is a function of aspect ratio at the rectangular end; the loss coefficient rises as the aspect ratio falls. The pressure drop slightly increases when the wall surface is roughened and is higher at low aspect ratios.     

Emission studies of the mechanism of gaseous biacetyl photolysis at 3450, 3650, 3880, and 4358 a and 28°C

The quantum yields of phosphorescence (Φ_p) of biacetyl have been determined in pure biacetyl, biacetyl-SO₂, and biacetyl-c-C₆H₁₂ mixtures in experiments using bands of radiation centered at 3450, 3650, 3880, and 4348 Å. It has been shown that the unexpected effect of gas concentration on the quantum yields of the sulfur dioxide triplet-sensitized phosphorescence of biacetyl resulted largely from the significant destruction of biacetyl triplets at the wall of the cell. The kinetics of the variation of Φ_p with [Ac₂], wavelength of the absorbed light, and added gases provide new estimates of the energy relations and the rate constants for the decomposition reaction of vibrationally rich biacetyl molecules in the first excited singlet state (¹Ac₂?): ¹Ac₂? → products (1), ¹Ac₂? + Ac₂ → ¹Ac₂ + Ac₂ (2); the minimum energy necessary in ¹Ac₂? for reaction (1) to occur is estimated to be about 72.8 kcal/mole above the ground state of biacetyl: k₁/k₂ = (4.3 ± 0.1) × 10^?3M at 3450 Å, (4.07 ± 0.04) × 10^?4M at 3650 Å, and (5.6 ± 0.4) × 10^?5M at about 3800 Å. The variation of the rate constant ratio is shown to be consistent with the expectations of the simple theory of excited molecule decomposition. Biacetyl triplet (³Ac₂) rate constants were determined by measurements of Φ_p in O₂ and NO-containing mixtures: ³Ac₂ + S → (Ac₂–S, products) (8); for O₂ = S, k₈ = (5.76 ± 0.40) × 10⁸ (3650 Å experiments), (5.76 ± 0.27) × 10⁸ (4358 Å); for NO = S, k₈ = (3.34 ± 0.20) × 10⁹ (3650 Å), (3.33 ± 0.18) × 10⁹ 1./mole-sec (4358 Å). A comparison between these and previous findings of the SO₂ triplet (³SO₂)-sensitized excitation of biacetyl [5,6] show that the decomposition of the initial ³Ac₂ product of the exothermic energy transfer reaction ³SO₂ + Ac₂ → SO₂ + ³Ac₂ is unimportant.     

The SO2-sensitized phosphorescence of biacetyl vapor in photolyses at 2650 and 2875 Å. The intersystem crossing ratio in sulfur dioxide

Quantum yields of the triplet sulfur dioxide (³SO₂)-sensitized phosphoresence (Φ_sens) in biacetyl (Ac₂) have been determined in experiments over a wide range of pressures of SO₂ and Ac₂. Excited singlet sulfur dioxide (¹SO₂) was generated using 2650-Å and 28757hyphen;Å light. The values of Φ_sens were dependent on the [SO₂]/[Ac₂] ratio, as anticpated theoretically. However, in runs at a fixed [SO₂]/[Ac₂] ratio, the measured Φ_sens values were dependent on the total pressure. This theoretically unexpected effect is probably largely the result of biacetyl triplet diffusion with deactivation at the cell wall. Treatment of the quantum yield data in terms of the complete mechanism gave new estimates of the following rate functions: ¹SO₂ + SO₂ → (2SO₂) (1), ¹SO₂ + SO₂ → ³SO₂ + SO₂ (2), k₂/(k₁ + k₂) = 0.082 ± 0.003 (2650 Å), 0.095 ± 0.005 (2875 Å) ³SO₂ + Ac₂ → SO₂ + ³Ac₂ (9a), ³SO₂ + Ac₂ → SO₂ + Ac₂ (9b), k_9a + k_9b = (8.4 ± 2.1) × 10¹⁰ (2650 Å), (8.1 ± 3.0) × 10¹⁰ l./mole-sec (2875 Å) ³SO₂ → SO₂ + hv_p (6), k₆ = (7.3 ± 1.3) × 10¹ sec^?1.     

Kinetics of fluorescence decay of SO2 excited in the 2662–3273 Å region

The kinetics of fluorescence decay of SO₂ excited in the 2975–3273 Å region was studied using a powerful, frequency doubled, tunable dye laser system. The existence of two emitting species, first observed by Brus and McDonald, was confirmed. The collision-free lifetimes of the long-lived (L) species ranged from 100 to 300 μsec and the short-lived (S) species from 17 to 43 μsec over the wavelength range employed. The magnitude of the bimolecular quenching rate constant for the L state was a function of the excitation energy; the data show that about 1 kcal/mol of internal energy is lost per collision of the SO₂(L) species excited in the range of 2998–3107 Å. Studies of the relative initial fluorescence intensity of the S to that of the L state (I_S°/I_L°) were made in experiments which extended to 0.11 mtorr. The pressure dependence of the I_S°/I_L° ratio for experiments at 3107, 3211, and 3225 Åproved that the S and L states do not decay independently. Either efficient bimolecular S → L conversion occurs or bimolecular S ? L interconversion of both states is important. These data coupled with spectroscopic studies of Hamada and Merer and Shaw and coworkers favor the designation of the S and L states as SO₂(¹A₂) and SO₂(¹B₁), respectively. However, if the assignment is correct, then the band origin of the ¹B₁ state must be at a somewhat longer wavelength, λ> 3273 Å than tentative spectroscopic assignments suggest. Bimolecular quenching rate constants for the L and S components with various atmospheric gases were determined in 3130- and 2662-Å studies.     

Chemical shifts for tritons in the ortho,meta and para positions of toluene as determined by tritium NMR spectroscopy

Chemical shifts for tritons in ortho, meta and para positions in toluene have been determined using a 64 MHz tritium NMR spectrometer. The order of shift is meta>para>ortho, whereas the calculated shift order for protons is meta>ortho>para.