An Empirical Study on Decision making for Quality Requirements

[Context] Quality requirements are important for product success yet often handled poorly. The problems with scope decision lead to delayed handling and an unbalanced scope. [Objective] This study characterizes the scope decision process to understand influencing factors and properties affecting the scope decision of quality requirements. [Method] We studied one company's scope decision process over a period of five years. We analyzed the decisions artifacts and interviewed experienced engineers involved in the scope decision process. [Results] Features addressing quality aspects explicitly are a minor part (4.41%) of all features handled. The phase of the product line seems to influence the prevalence and acceptance rate of quality features. Lastly, relying on external stakeholders and upfront analysis seems to lead to long lead-times and an insufficient quality requirements scope. [Conclusions] There is a need to make quality mode explicit in the scope decision process. We propose a scope decision process at a strategic level and a tactical level. The former to address long-term planning and the latter to cater for a speedy process. Furthermore, we believe it is key to balance the stakeholder input with feedback from usage and market in a more direct way than through a long plan-driven process

Chiral Symmetry Breaking in a Soft-Wall Model of AdS/QCD

We incorporate chiral symmetry breaking in a soft-wall version of the AdS/QCD model by using a modified dilaton profile and a quartic term in the bulk scalar potential. This allows one to separate the dependence on spontaneous and explicit chiral symmetry breaking. The resulting mass spectra in the scalar, vector and axial-vector sectors compares favorably with the respective QCD resonances.Comment: Proceedings of "Crossing the Boundaries: Gauge Dynamics at Strong Coupling", Minneapolis, 2009. 12 pages, 7 figure

Partially Composite Dynamical Dark Matter

In this paper, we consider a novel realization of the Dynamical Dark Matter (DDM) framework in which the ensemble of particles which collectively constitute the dark matter are the composite states of a strongly-coupled conformal field theory. Cosmological abundances for these states are then generated through mixing with an additional, elementary state. As a result, the physical fields of the DDM dark sector at low energies are partially composite -- i.e., admixtures of elementary and composite states. Interestingly, we find that the degree of compositeness exhibited by these states varies across the DDM ensemble. We calculate the masses, lifetimes, and abundances of these states -- along with the effective equation of state of the entire ensemble -- by considering the gravity dual of this scenario in which the ensemble constituents are realized as the Kaluza-Klein states associated with a scalar propagating within a slice of five-dimensional anti-de Sitter (AdS) space. Surprisingly, we find that the warping of the AdS space gives rise to parameter-space regions in which the decay widths of the dark-sector constituents vary non-monotonically with their masses. We also find that there exists a maximum degree of AdS warping for which a phenomenologically consistent dark-sector ensemble can emerge. Our results therefore suggest the existence of a potentially rich cosmology associated with partially composite DDM.Comment: 25 pages, LaTeX, 6 figures, 1 tabl

Redox Stable Anode Materials for SOFC Application

The common material design for solid-oxide fuel cells (SOFCs) is based on the cermet (ceramic-metal composite) material group, for example anode compositions like nickel with yttria stabilized zirconia (Ni/YSZ). One of the main limitations of these material groups is that they may undergo unwanted thermal expansion during redox cycles, causing dimensional instability at the anode. The state-of-the-art Ni/YSZ anode experiences a linear expansion of up to 1% when oxidized, causing an irreversible microstructural change, decreasing the electrochemical activity. The problem cumulatively increases if the cell design is anode supported as this puts the electrolyte under tension, causing it to crack and leaking the fuel and oxidant gases. Currently researchers are focusing on the development of new SOFC anodes for internal reforming, lower temperature operation, and poison resistance, but there is a lack of study on the redox stability of these newly developed materials.;In this thesis work, the fundamental development of redox stable anode materials has been undertaken. Materials from perovskite, double perovskite, scheelite and double rutile structures has been considered. The material compositions include CeNb1-xWxO4, CeNb1-xMo xO4, Sr2Mg1-xMo1+x O6 (x = 0, 0.1, 0.2), Nb2TiO7 and Nb 1.33Ti0.67O4. The thermo mechanical and electrical redox stability of the various novel materials were tested by controlled-atmosphere dilatometry and four-point probe DC electrical conductivity respectively at SOFC operating temperature (800°C). Based on the thermo mechanical and electrical redox results, several doping strategies were adopted in the material systems to improve their redox stability while maintaining the coefficient of Thermal Expansion (CTE) at a minimum. The qualified material system was subjected to symmetrical and fuel cell tests to analyze the polarization resistance of novel anode material as well as electrochemical activity via in situ EIS.;It was found that in CeNbO4 material group, W and Mo doping seized the phase transition of CeNbO4 from monoclinic to tetragonal at elevated temperature. Also the CTE of CeNbO4 in air between 25 -- 800°C was considerably brought down from 20.77 to 13-14x10-6 K -1 by adopting this doping strategy. Regarding Nb2TiO 7 and Nb1.33Ti0.67O4 materials, though these materials exhibit stable phase transformation, Nb2TiO 7 as a starting SOFC composition is not ideal due to poor electrical properties (1.35 S/cm in reducing atmosphere at 800°C). Whereas, though Nb1.33Ti0.67O4 recorded a conductivity of 85 S/cm in reducing condition, the material is mechanically not stable under redox condition at 800°C. In Sr2Mg1-xMo1+x O6 (x = 0, 0.1, 0.2) material system, the material with Sr 2Mg0.9Mo1.1O6-delta composition was made both mechanically and electrical redox stable at 800°C, with a CTE of 14.5x10-6 K-1 in air between 25 -- 800°C and electrical conduction of 0.1 S/cm in air and 17.5 S/cm in reducing atmosphere. From symmetrical cell analysis, it was analyzed that Sr2Mg 0.9Mo1.1O6-delta had a low polarization resistance of 0.35 O cm2 at 800°C which make it a potential SOFC anode material

Naturalizing Supersymmetry with a Two-Field Relaxion Mechanism

We present a supersymmetric version of a two-field relaxion model that naturalizes tuned versions of supersymmetry. This arises from a relaxion mechanism that does not depend on QCD dynamics and where the relaxion potential barrier height is controlled by a second axion-like field. During the cosmological evolution, the relaxion rolls with a nonzero value that breaks supersymmetry and scans the soft supersymmetric mass terms. Electroweak symmetry is broken after the soft masses become of order the supersymmetric Higgs mass term and causes the relaxion to stop rolling for superpartner masses up to $\sim 10^9$ GeV. This can explain the tuning in supersymmetric models, including split-SUSY models, while preserving the QCD axion solution to the strong CP problem. Besides predicting two very weakly-coupled axion-like particles, the supersymmetric spectrum may contain an extra Goldstino, which could be a viable dark matter candidate.Comment: 33 pages, 3 figures; v2: bounds and figures correcte

Cruise Crimes: Economic-Legal Issues and Current Debates

Cruise tourism is one of the sunshine sectors of international tourism and is growing rapidly in many parts of the world. It is estimated that the growth rate of cruise tourism is twice the rate of tourism overall. Notwithstanding all the positives that accompany this growth, many critics have drawn attention to the “dark side” of cruise crimes. The eco-system aboard the cruise ship offers a fertile ground for the occurrence of crimes. The present paper examines the issue of crimes onboard from multiple standpoints and suggests some remedial measures that would lead to better management of cruise crimes. A presentation of the recent initiatives by the U.S. legislative bodies aimed at containing cruise crimes is also provided.cruise ships; criminology aboard; cruise crime typology; crime prevention; industry initiative; legislative intervention; and USA

Bonos convertibles contingentes y su impacto en las conductas de riesgo de los directivos

This paper discusses how contingent convertible bonds (CCB) influence the risktaking behaviour of managers. A methodology to measure the impact is presented. The results show that the decision of issuing CCB to finance company assets sets incentives to managers to increase risk, if it is not adjusted to the compensation system. However, if the remuneration of managers is adjusted simultaneously with the issuance, e.g. with internal debt, the drawbacks of the sole compensation with stock options can be equalised. Furthermore, it was found that CCB does have an impact on the risk-taking behaviour, while CCB does not change the incentive to increase the company value at allSe analiza cómo los bonos convertibles contingentes (CCB) influyen las conductas deriesgo de los directivos. Se presenta una metodología para medir el impacto. Los resultados muestran que la decisión de emitir los CCB para financiar la empresa incentiva a los directivos a conductas más arriesgadas, si no se ajusta el sistema de compensación. Sin embargo, si la remuneracíon de los directivos se ajusta simultáneamente con la emisión, p.ej. con deuda interna, los inconvenientes de una única compensación con opciones se compensarían. Además, hemos encontrado que los CCB no cambian los incentivos para aumentar el valor de la empresa en general