Nonlinear waves in solids with slow dynamics: an internal-variable model

In heterogeneous solids such as rocks and concrete, the speed of sound diminishes with the strain amplitude of a dynamic loading (softening). This decrease known as "slow dynamics" occurs at time scales larger than the period of the forcing. Also, hysteresis is observed in the steady-state response. The phenomenological model by Vakhnenko et al. is based on a variable that describes the softening of the material [Phys. Rev. E 70-1, 2004]. However, this model is 1D and it is not thermodynamically admissible. In the present article, a 3D model is derived in the framework of the finite strain theory. An internal variable that describes the softening of the material is introduced, as well as an expression of the specific internal energy. A mechanical constitu-tive law is deduced from the Clausius-Duhem inequality. Moreover, a family of evolution equations for the internal variable is proposed. Here, an evolution equation with one relaxation time is chosen. By construction, this new model of continuum is thermodynamically admissible and dissipative (inelas-tic). In the case of small uniaxial deformations, it is shown analytically that the model reproduces qualitatively the main features of real experiments

Mercury deposition in southern New Hampshire, 2006–2009

The atmospheric deposition of mercury (Hg) occurs via several mechanisms including wet, dry, and occult processes. In an effort to understand the atmospheric cycling and seasonal depositional characteristics of Hg, event-based wet deposition samples and reactive gaseous Hg (RGM) measurements were collected for approximately 3 years at Thompson Farm (TF), a near-coastal rural site in Durham, NH, part of the University of New Hampshire AIRMAP Observing Network. Total aqueous mercury exhibited seasonal patterns in Hg wet deposition at TF. The lowest Hg wet deposition was measured in the winter with an average total seasonal deposition of 1.56 μg m−2compared to the summer average of 4.71 μg m−2. Inter-annual differences in total wet deposition are generally linked with precipitation volume, with the greatest deposition occurring in the wettest year. Relationships between surface level RGM and Hg wet deposition were also investigated based on continuous RGM measurements at TF from November 2006 to September 2009. No correlations were observed between RGM mixing ratios and Hg wet deposition, however the ineffective scavenging of RGM during winter precipitation events was evidenced by the less frequent depletion of RGM below the detection level. Seasonal dry deposition of reactive gaseous Hg (RGM) was estimated using an order-of-magnitude approach. RGM mixing ratios and dry deposition estimates were greatest during the winter and spring. The seasonal ratios of Hg wet deposition to RGM dry deposition vary by up to a factor of 80

Ethical belief and ethical intention : Comparing South African and Polish commerce students’ perceptions

Abstract: The purpose of this study was to address the differences between the ethical intentions and beliefs of students in business studies in South Africa and Poland. The target population was all full-time students, registered for a commerce degree at selected higher education (tertiary) institutions in South Africa and Poland. The measuring instrument was a self-administered questionnaire which presented seven ethical scenarios to respondents to which they provided a yes/no response to each part of the question. Probability sampling was used, and the convenient sampling technique applied to select the sample. Chi-squared analysis was performed on the data to test the stated null hypotheses at a 95% confidence level. The imminent conclusion that flows from the study is that differences do exist between the ethical beliefs and ethical intentions of business students in South Africa and Poland, but these differences seem to be fairly similar across both countries

Antecedents and outcomes of satisfaction in buyer-supplier relationships in South Africa: A replication study

Abstract: The purpose of this study was to validate the proposition that in a business buyersupplier relationship, the variables trust and commitment influence satisfaction. Satisfaction then influences cooperation, coordination and continuity. A research model showing the hypothesised relationships was first tested in an original study before being replicated in the current study. Both the original and replication studies followed a quantitative approach and targeted large companies in South Africa. In the original study, data was collected from 500 large South African companies while in the replication study data was collected from 250 large companies. Structural equation modelling (SEM) was used to analyse the data. The results in both studies provide support for the proposed model in the study

South African corporate ethics codes : establishment and communication

Abstract: The focus of this study is on the top 500 companies in South Africa (as per the TopCo 2014 list) that have a code of ethics, in order to see the current state of development in this area after twenty years of focus by the government and business on making corporate South Africa a more ethical environment in which to conduct business. Methodology – A structured questionnaire survey method was used to gather the data, and it was directed to the company secretaries of these top 500 companies. Findings – Many companies in South Africa have a well-established set of protocols to enact the ethos of their code of ethics, indicating that they are becoming increasingly aware of the benefits to them of having a code. South African companies are therefore implementing both a code of ethics and strategies that contribute to creating an ethical corporate culture

Exploring parental and driver knowledge, use and beliefs of child restraints such as infant car seats, toddler seats and booster seats in South Africa

Abstract: The purpose of this paper is to determine parents’ and drivers’ knowledge, use and beliefs of child restraints amongst lower middle-class groups in South Africa. The study was qualitative in nature, and data was collected from parents or drivers of children aged birth - 11 with a motor vehicle in Gauteng. Through the application of the convenience sampling technique, a total of 14 parents and drivers with children at selected pre-schools and primary schools, who are in the lower middleclass groups and who reside in the cities of Johannesburg, Tshwane and Ekurhuleni, were selected. The Morse and Field Approach was used to analyse the data because the steps of this data analysis method are clear, easy to follow and comprehensible. There is a lack of knowledge and usage of child restraints among lower middle-class parents and drivers within Gauteng. The results also indicate that there are variables that are predictive of age-appropriate restraint use and knowledge, and that parents hold specific beliefs around child restraints. Lastly, the results indicated that the parents and drivers have rarely seen any advertisements on child restraints in South Africa. By exploring the topic of usage, knowledge, beliefs and the social marketing of child restraints, strategies have been identified on how to overcome the major challenge of child injuries in motor vehicle accidents in South Africa. This study promotes child restraint usage on South African roads and assists organisations in South Africa to better understand that social marketing is necessary to change the behaviour of parents with regard to child restraints usage

Events, processes, and the time of a killing

The paper proposes a novel solution to the problem of the time of a killing (ToK), which persistently besets theories of act-individuation. The solution proposed claims to expose a crucial wrong-headed assumption in the debate, according to which ToK is essentially a problem of locating some event that corresponds to the killing. The alternative proposal put forward here turns on recognizing a separate category of dynamic occurents, viz. processes. The paper does not aim to mount a comprehensive defense of process ontology, relying instead on extant defenses. The primary aim is rather to put process ontology to work in diagnosing the current state of play over ToK, and indeed in solving it

Operation and post-test inspection of the SNAP-8 pre-prototype boiler P/N CF 751840, S/N 2

Performance testing of SNAP 8 boile

Vibration tests with the SNAP-8 condenser P/N 093945-1, S/N A-1

Environmental vibration testing of SNAP 8 condenser and design evaluation for space and launch condition

The size of two-body weakly bound objects : short versus long range potentials

The variation of the size of two-body objects is investigated, as the separation energy approaches zero, with both long range potentials and short range potentials having a repulsive core. It is shown that long range potentials can also give rise to very extended systems. The asymptotic laws derived for states with angular momentum l=1,2 differ from the ones obtained with short range potentials. The sensitivity of the asymptotic laws on the shape and length of short range potentials defined by two and three parameters is studied. These ideas as well as the transition from the short to the long range regime for the l=0 case are illustrated using the Kratzer potential.Comment: 5 pages, 3 figures, submitted to Physical Review Letter