Exergoeconomic analysis of a thermochemical copper–chlorine cycle for hydrogen production using specific exergy cost (SPECO) method

The manner is investigated in which exergy-related parameters can be used to minimize the cost of a copper–chlorine (Cu–Cl) thermochemical cycle for hydrogen production. The iterative optimization technique presented requires a minimum of available data and provides effective assistance in optimizing thermal systems, particularly in dealing with complex systems and/or cases where conventional optimization techniques cannot be applied. The principles of thermoeconomics, as embodied in the specific exergy cost (SPECO) method, are used here to determine changes in the design parameters of the cycle that improve the cost effectiveness of the overall system. The methodology provides a reasonable approach for improving the cost effectiveness of the Cu–Cl cycle, despite the fact that it is still in development. It is found that the cost rate of exergy destruction varies between $1 and $15 per kilogram of hydrogen and the exergoeconomic factor between 0.5 and 0.02 as the cost of hydrogen rises from $20 to $140 per GJ of hydrogen energy. The hydrogen cost is inversely related to the exergoeconomic factor, plant capacity and exergy efficiency. The results are expected to assist ongoing efforts to increase the economic viability and to reduce product costs of potential commercial versions of this process. The impact of the results are anticipated to be significant since thermochemical water splitting with a copper–chlorine cycle is a promising process that could be linked with nuclear reactors to produce hydrogen with no greenhouse gases emissions, and thereby help mitigate numerous energy and environment concerns.     

Low Rank Approximation of a Hankel Matrix by Structured Total Least Norm

The structure preserving rank reduction problem arises in many important applications. The singular value decomposition (SVD), while giving the closest low rank approximation to a given matrix in matrix L ₂ norm and Frobenius norm, may not be appropriate for these applications since it does not preserve the given structure. We present a new method for structure preserving low rank approximation of a matrix, which is based on Structured Total Least Norm (STLN). The STLN is an efficient method for obtaining an approximate solution to an overdetermined linear system AX B, preserving the given linear structure in the perturbation [E F] such that (A + E)X = B + F. The approximate solution can be obtained to minimize the perturbation [E F] in the L _p norm, where p = 1, 2, or . An algorithm is described for Hankel structure preserving low rank approximation using STLN with L _p norm. Computational results are presented, which show performances of the STLN based method for L ₁ and L ₂ norms for reduced rank approximation for Hankel matrices.     

Multiple Wick Product Chaos Processes

Let u(x) xR ^q be a symmetric nonnegative definite function which is bounded outside of all neighborhoods of zero but which may have u(0)=. Let p _x, (·) be the density of an R ^q valued canonical normal random variable with mean x and variance and let {G _x, ; (x, )R ^q ×[0,1 ]} be the mean zero Gaussian process with covariance

Superior laryngeal nerve paresis and paralysis

Superior laryngeal nerve paresis and paralysis are relatively common but often difficult to diagnose with certainty. They are most commonly caused by viral infections, though other etiologies must be considered. A thorough history and physical examination, including strobovideolaryngoscopy and laryngeal electromyography, are needed for definitive diagnosis. It is essential to establish the diagnosis accurately to differentiate an apparent superior laryngeal nerve paresis from other conditions, such as myasthenia gravis. Laryngeal electromyography is used to confirm clinical impressions, as a guide for therapy, and as one measure of recovery. In our experience, accurate and early diagnosis assure the best phonatory outcome by directing therapy that will prevent or eliminate compensatory vocal abuses, which may themselves lead to even more serious vocal injury.     

Necessity and sufficiency of f being a divergence for vanishing of variational derivatives of f: General case

Concise proofs are presented for the necessity and sufficiency of f being a divergence for the variational derivatives of f to vanish identically, where f is a function of N functions of n variables, their partial derivatives to arbitrary order, and the n variables. The approach is conventional.     

Temperature and magnetic field dependence of the elastic properties of rare earth-cobalt laves phase compounds

Ultrasonic sound velocity measurements have been carried out in order to determine the elastic moduli, adiabatic compressibility and the Debye temperature of polycrystalline rare earth-cobalt Laves phase compounds RCo₂(R = Pr, Nd, Sm, Gd, Tb, Dy, Ho, ErandLu) and YCo₂ between 4.2 and 300 K. DyCo₂ HoCo₂ and ErCo₂ exhibit a first-order transition at T_c. In SmCo₂ and TbCo₂ the phase transition is of the second-order accompanied by a large lattice softening. NdCo₂, GdCo₂ and HoCo₂ show spin reorientations from one easy direction of magnetization to another one, at low temperatures, below T_c.The influence of an external magnetic field (up to 25 kOe) on the elastic properties of these Laves phases, the so-called ΔE effect was determined. No saturation was reached in SmCo₂, TbCo₂ and DyCo₂ in magnetic fields up to 25 kOe. The behavior of the RCo₂ compounds was compared with that of RFe₂, published earlier.     

The reaction of carboxylic acid hydrazides with formaldehyde

The hydrazides of benzoic, phenyacetic, and 3-phenylpropionic acids react with an acidic solution of formaldehyde to give 15 . Similar treatment of the corresponding methylhydrazides gave 16 . The ethers 15 can be cleaved to give, after methylation, 16 . Spectral data for 15 and 16 are presented.     

Space-time microstructure and singularity-free quantum field theory

It is shown that the dynamical consistency requirements of quantum field theory and the Lorentz-invariant character of particle kinematics and wave equations are compatible with the postulate that physical space is a complex manifold with Euclidean-Gaussian measure in the small. Such a postulate for the microstructure of space introduces a fundamental length(10^–16 cm) and leads to-functions that are analytic on the light-cone for a free field, and hence to self-energies and renormaiization constants that are finite for interacting fields.Work supported by a National Science Foundation grant.     

Conventional formulations of Noether's theorem in classical field theory

The role of invariance considerations in conventional formulations of Noether's theorem in classical field theory is investigated and found weaker than is usually supposed. It is shown how nonfulfilment of the conventional assumptions going into Noether's theorem brings about nonconservation.     

Temperature and magnetic field dependence of the elastic properties of the HoxTb1−xCo2 Laves phase compounds

Ultrasonic sound velocity measurements have been carried out in order to determine the adiabatic compressibility and elastic moduli of the pseudobinary Ho_xTb_1?xCo₂ Laves phase compounds. The anomalies, associated with the Curie temperatures and the presence of various spin reorientations, allowed the determination of the spin orientation diagram of the system. The similarity of this spin orientation diagram with that previously established of the Ho_xTb_1?xFe₂ system strongly supports the single rare earth ion model for the magnetic anisotropy behavior of the compounds studied. Measurements carried out in an external magnetic field revealed the presence of a significant ΔE effect.