5,751 research outputs found
Allocating Safety Cost using in Construction Site
Environments, Health, and Safety (EHS) activities are strongly linked to the concept of sustainability in the current construction industry and consequently absorb more financial and managerial attention. One of major obstacles in EHS costing is that most EHS costs are buried in general overhead costs. Therefore, EHS costs lacks transparency, making it hard to allocate EHS costs to relevant construction projects. This paper present a recent study in which a method of activity-based costing (ABC) has been applied to safety costs at a contractor’s home office. The list of safety activities, their cost drivers as well as their cost information on one of Korean general contractor is provided. The authors expect that the application of ABC will improve transparency in costing EHS costs as well as allocating EHS costs to projects
Role of thermal friction in relaxation of turbulent Bose-Einstein condensates
In recent experiments, the relaxation dynamics of highly oblate, turbulent
Bose-Einstein condensates (BECs) was investigated by measuring the vortex decay
rates in various sample conditions [Phys. Rev. A , 063627 (2014)] and,
separately, the thermal friction coefficient for vortex motion was
measured from the long-time evolution of a corotating vortex pair in a BEC
[Phys. Rev. A , 051601(R) (2015)]. We present a comparative analysis of
the experimental results, and find that the vortex decay rate is
almost linearly proportional to . We perform numerical simulations of
the time evolution of a turbulent BEC using a point-vortex model equipped with
longitudinal friction and vortex-antivortex pair annihilation, and observe that
the linear dependence of on is quantitatively accounted for
in the dissipative point-vortex model. The numerical simulations reveal that
thermal friction in the experiment was too strong to allow for the emergence of
a vortex-clustered state out of decaying turbulence.Comment: 7 pages, 5 figure
Identification and Evaluation of the Influencing Factors in Target Value Design Process through an Industry Survey
Target value design is a new practice in the construction industry promoting concurrent engineering and collaborative design. This paper shows the results of literature survey to identify the influencing factors in the target value design. The paper also presents the results of a questionnaire survey to explore the industry practitioners' perception of the relative importance of the influencing factors. Project stakeholders participating in the survey consider the integration of different project stakeholders in the design phase as critical. The project definition is also regarded as essential in implementing the target value design. However, the market conditions and project attributes are considered as least significant in the target value design process
Technical Efficiency in the Iron and Steel Industry: A Stochastic Frontier Approach
In this paper we examine the technical efficiency of firms in the iron and steel industry and try to identify the factors contributing to the industry's efficiency growth, using a time-varying stochastic frontier model. Based on our findings, which pertain to 52 iron and steel firms over the period of 1978-1997, POSCO and Nippon Steel were the most efficient firms, with their production, on average, exceeding 95 percent of their potential output. Our findings also shed light on possible sources of efficiency growth in the industry. If a firm is government-owned, its privatization is likely to improve its technical efficiency to a great extent. A firm's technical efficiency also tends to be positively related to its production level as measured by a share of the total world production of crude steel. Another important source of efficiency growth identified by our empirical findings is adoption of new technologies and equipment. Our findings clearly indicate that continued efforts to update technologies and equipment are critical in pursuit of efficiency in the iron and steel industry.
Nanomechanical characterization of quantum interference in a topological insulator nanowire
The discovery of two-dimensional gapless Dirac fermions in graphene and
topological insulators (TI) has sparked extensive ongoing research toward
applications of their unique electronic properties. The gapless surface states
in three-dimensional insulators indicate a distinct topological phase of matter
with a non-trivial Z2 invariant that can be verified by angle-resolved
photoemission spectroscopy or magnetoresistance quantum oscillation. In TI
nanowires, the gapless surface states exhibit Aharonov-Bohm (AB) oscillations
in conductance, with this quantum interference effect accompanying a change in
the number of transverse one-dimensional modes in transport. Thus, while the
density of states (DOS) of such nanowires is expected to show such AB
oscillation, this effect has yet to be observed. Here, we adopt nanomechanical
measurements that reveal AB oscillations in the DOS of a topological insulator.
The TI nanowire under study is an electromechanical resonator embedded in an
electrical circuit, and quantum capacitance effects from DOS oscillation
modulate the circuit capacitance thereby altering the spring constant to
generate mechanical resonant frequency shifts. Detection of the quantum
capacitance effects from surface-state DOS is facilitated by the small
effective capacitances and high quality factors of nanomechanical resonators,
and as such the present technique could be extended to study diverse quantum
materials at nanoscale.Comment: 15+16 pages, 4+11 figure
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