Transient stress evolution in repulsion and attraction dominated glasses

We present results from microscopic mode coupling theory generalized to colloidal dispersions under shear in an integration-through-transients formalism. Stress-strain curves in start-up shear, flow curves, and normal stresses are calculated with the equilibrium static structure factor as only input. Hard spheres close to their glass transition are considered, as are hard spheres with a short-ranged square-well attraction at their attraction dominated glass transition. The consequences of steric packing and physical bond formation on the linear elastic response, the stress release during yielding, and the steady plastic flow are discussed and compared to experimental data from concentrated model dispersions.Comment: J. Rheol., 58, in prin

Identification of drivers, benefits, and challenges of ISO 50001 through case study content analysis

An expanding body of research is defining drivers, benefits, and challenges of adopting ISO 50001 energy management systems. The Clean Energy Ministerial's Energy Management Leadership Awards program requires ISO 50001-certified organizations to develop case studies of their implementation experience. 72 recent case studies spanning multiple economic sectors provide a unique global look at implementation from certified organizations' perspectives. This dataset was investigated through content analysis of phrases related to motivations and goals, the role of management and the organization, benefits achieved, keys to success, and challenges. This paper presents findings from this quantitative analysis of “codes” assigned to phrases that capture their meaning. While organizations adopted ISO 50001 for different motives and saw myriad benefits beyond energy savings and associated greenhouse gas emissions reductions, commonalities exist. The most frequently identified drivers are existing values and goals, environmental sustainability, and government incentives or regulations. Findings also include: obtaining and sustaining top management support is critical; top benefits mentioned are cost savings, productivity, and operational improvements; and the primary barrier is lacking a culture of energy management. Policymakers and others looking to accelerate ISO 50001 uptake can use these findings to highlight benefits and incentives that will resonate with corporate decisionmakers worldwide

Non--Newtonian viscosity of interacting Brownian particles: comparison of theory and data

A recent first-principles approach to the non-linear rheology of dense colloidal suspensions is evaluated and compared to simulation results of sheared systems close to their glass transitions. The predicted scenario of a universal transition of the structural dynamics between yielding of glasses and non-Newtonian (shear-thinning) fluid flow appears well obeyed, and calculations within simplified models rationalize the data over variations in shear rate and viscosity of up to 3 decades.Comment: 6 pages, 2 figures; J. Phys. Condens. Matter to be published (Jan. 2003

Simple Current Actions of Cyclic Groups

Permutation actions of simple currents on the primaries of a Rational Conformal Field Theory are considered in the framework of admissible weighted permutation actions. The solution of admissibility conditions is presented for cyclic quadratic groups: an irreducible WPA corresponds to each subgroup of the quadratic group. As a consequence, the primaries of a RCFT with an order n integral or half-integral spin simple current may be arranged into multiplets of length k^2 (where k is a divisor of n) or 3k^2 if the spin of the simple current is half-integral and k is odd.Comment: Added reference, minor change

Employee Response to Compulsory Short-Time Work

This paper reports the results of a survey of over 1500 employees who faced compulsory reductions of 10 percent in hours of work and earnings during the second half of 1985. The workers were asked how they used the free time and how they viewed the program, and their answers were analyzed in relation to their economic and social characteristics. On average, the workers spent 12 percent of the free time in uncompensated work for the company, 43 percent in other work (mostly housework, childcare, and other nonmarket chores), and 45 percent in leisure-time activities such as resting, reading, and hobbies. Ceteris paribus, education and income were positively related to percentage of time spent in company work, and age was negatively related. Time spent in other work rose with the presence of children, especially for women. Employee reaction to the program was generally favorable; married women were most positive and married men least positive. Workers 45 years of age and over were significantly more positive than those 35-44. There was a strong connection between time use and reaction to the program; workers who spent more of their free time working without pay at the company or in home production were much less positive than those who spent more time in leisure activities.

The relativistic self-energy in nuclear dynamics

It is a well known fact that Dirac phenomenology of nuclear forces predicts the existence of large scalar and vector mean fields in matter. To analyse the relativistic self-energy in a model independent way, modern high precision nucleon-nucleon ($NN$) potentials are mapped on a relativistic operator basis using projection techniques. This allows to compare the various potentials at the level of covariant amplitudes were a remarkable agreement is found. It allows further to calculate the relativistic self-energy in nuclear matter in Hartree-Fock approximation. Independent of the choice of the nucleon-nucleon interaction large scalar and vector mean fields of several hundred MeV magnitude are generated at tree level. In the framework of chiral EFT these fields are dominantly generated by contact terms which occur at next-to-leading order in the chiral expansion. Consistent with Dirac phenomenology the corresponding low energy constants which generate the large fields are closely connected to the spin-orbit interaction in $NN$ scattering. The connection to QCD sum rules is discussed as well.Comment: 49 pages, 13 figure

S_4-symmetry of 6j-symbols and Frobenius-Schur indicators in rigid monoidal C^*-categories

We show that a left-rigid monoidal C^*-category with irreducible monoidal unit is also a sovereign and spherical category. Defining a Frobenius-Schur type indicator we obtain selection rules for the fusion coefficients of irreducible objects. As a main result we prove S_4-invariance of 6j-symbols in such a category.Comment: 21 pages + 16 pages with figures; LaTeX2e plus macro package XYpic; file with included pictures available as http://www.desy.de/~jfuchs/s4/s4.ps.g

Variable-speed Generators with Flux Weakening

A cost-competitive, permanent-magnet 20 kW generator is designed such that the following criteria are satisfied: an (over) load capability of at least 30 kW over the entire speed range of 60-120 rpm, generator weight of about 550 lbs with a maximum radial stator flux density of 0.82 T at low speed, unity power factor operation, acceptably small synchronous reactances and operation without a gear box. To justify this final design four different generator designs are investigated: the first two designs are studied to obtain a speed range from 20 to 200 rpm employing rotor field weakening, and the latter two are investigated to obtain a maximum speed range of 40 to 160 rpm based on field weakening via the stator excitation. The generator reactances and induced voltages are computed using finite element/difference solutions. Generator losses and efficiencies are presented for all four designs at rated temperature of Tr=120C