87,148 research outputs found

    Seven coordinate molybdenum and tungsten complexes containing Tpm and Tpm derivatives and the impact of ligand substitution on NMR chemical shifts

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    A series of known and new seven coordinate molybdenum and tungsten complexes of tris(pyrazolyl)methane (Tpm) and substituted Tpm, [TpmM(CO)3X]+, have been synthesized. Depending on the identity of X, (bromo, iodo, hydrido) and the substitution of the Tpm ligand, substantial chemical shift differences are observed for the hydrogen on the central carbon of the Tpm ligand. Factors impacting the chemical shift of the hydrogen on the central carbon of the Tpm ligand, such as the electron donating ability of the Tpm ligand and the electronegativity of the additional ligand on the metal, will be discussed

    An investigation into current production challenges facing the Libyan cement industry and the need for innovative Total Productive Maintenance (TPM) strategy

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    Purpose - The purpose of this paper is to investigate maintenance and production problems in the cement industry in Libya with particular emphasis on future implementation of Total Productive Maintenance (TPM). Methodology/ Approach - The paper presents the use of case study approach of production data and history, field visits, a survey methodology using a detailed questionnaire with employees and interviews with top and middle managers in four cement factories. Findings - It has been found that the four factories under investigation have low productivity and production levels when compared with the design values. There is no clear TPM strategy and it has been also found that the lack of training and personal development is the main cause of this problem. In addition, employees are found not to be motivated as a result of the lack of poor management strategy and reward structure. Implications - Based on the findings, a new framework for TPM has been developed. This TPM strategy could be implemented in other Libyan factories as a result of the potential similarities in the cultural and environmental aspects. Practical implications - The current challenges have been identified and comparative analysis is developed into a model for the implementation of TPM. Originality/Value of pape r- The paper highlights limitation is the cement factories in Libya in relation to TPM and production strategies. The importance of adopting a realistic strategy and framework by managers is discussed. This work is developed as collaboration between Academia and Libyan Cement industry for solving productivity problems and develop a strategic framework of TPM for improving the Libyan industry

    Change management and implementation of total productive maintenance: an exploratory study of Malaysian manufacturing companies

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    This study examines the effects of change management towards the implementation of productivity and quality improvement programs through the concept of Total Productive Maintenance (TPM), in manufacturing firms in Malaysia. The factors measured are management commitment, training and education, employee empowerment, team culture and company policies and goals for change management. Autonomous maintenance and planned maintenance factors were used to measure TPM. The findings of the study provide empirical evidence that change management factors significantly enhances the extent of TPM implementatio

    The Random-Diluted Triangular Plaquette Model: study of phase transitions in a Kinetically Constrained Model

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    We study how the thermodynamic properties of the Triangular Plaquette Model (TPM) are influenced by the addition of extra interactions. The thermodynamics of the original TPM is trivial, while its dynamics is glassy, as usual in Kinetically Constrained Models. As soon as we generalize the model to include additional interactions, a thermodynamic phase transition appears in the system. The additional interactions we consider are either short ranged, forming a regular lattice in the plane, or long ranged of the small-world kind. In the case of long-range interactions we call the new model Random-Diluted TPM. We provide arguments that the model so modified should undergo a thermodynamic phase transition, and that in the long-range case this is a glass transition of the "Random First-Order" kind. Finally, we give support to our conjectures studying the finite temperature phase diagram of the Random-Diluted TPM in the Bethe approximation. This corresponds to the exact calculation on the random regular graph, where free-energy and configurational entropy can be computed by means of the cavity equations.Comment: 20 pages, 7 figures; final version to appear on PR

    Citizen Electronic Identities using TPM 2.0

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    Electronic Identification (eID) is becoming commonplace in several European countries. eID is typically used to authenticate to government e-services, but is also used for other services, such as public transit, e-banking, and physical security access control. Typical eID tokens take the form of physical smart cards, but successes in merging eID into phone operator SIM cards show that eID tokens integrated into a personal device can offer better usability compared to standalone tokens. At the same time, trusted hardware that enables secure storage and isolated processing of sensitive data have become commonplace both on PC platforms as well as mobile devices. Some time ago, the Trusted Computing Group (TCG) released the version 2.0 of the Trusted Platform Module (TPM) specification. We propose an eID architecture based on the new, rich authorization model introduced in the TCGs TPM 2.0. The goal of the design is to improve the overall security and usability compared to traditional smart card-based solutions. We also provide, to the best our knowledge, the first accessible description of the TPM 2.0 authorization model.Comment: This work is based on an earlier work: Citizen Electronic Identities using TPM 2.0, to appear in the Proceedings of the 4th international workshop on Trustworthy embedded devices, TrustED'14, November 3, 2014, Scottsdale, Arizona, USA, http://dx.doi.org/10.1145/2666141.266614

    Probing DNA conformational changes with high temporal resolution by Tethered Particle Motion

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    The Tethered Particle Motion (TPM) technique informs about conformational changes of DNA molecules, e.g. upon looping or interaction with proteins, by tracking the Brownian motion of a particle probe tethered to a surface by a single DNA molecule and detecting changes of its amplitude of movement. We discuss in this context the time resolution of TPM, which strongly depends on the particle-DNA complex relaxation time, i.e. the characteristic time it takes to explore its configuration space by diffusion. By comparing theory, simulations and experiments, we propose a calibration of TPM at the dynamical level: we analyze how the relaxation time grows with both DNA contour length (from 401 to 2080 base pairs) and particle radius (from 20 to 150~nm). Notably we demonstrate that, for a particle of radius 20~nm or less, the hydrodynamic friction induced by the particle and the surface does not significantly slow down the DNA. This enables us to determine the optimal time resolution of TPM in distinct experimental contexts which can be as short as 20~ms.Comment: Improved version, to appear in Physical Biology. 10 pages + 10 pages of supporting materia

    Determination of physical properties of the asteroid (41) Daphne from interferometric observations in the thermal infrared

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    We describe interferometric observations of the asteroid (41) Daphne in the thermal infrared obtained with the Mid-Infrared Interferometric Instrument (MIDI) of the Very Large Telescope Interferometer (VLTI). We derived the size and the surface thermal properties of (41) Daphne by means of a thermophysical model (TPM), which is used for the interpretation of interferometric data for the first time. From our TPM analysis, we derived a volume equivalent diameter for (41) Daphne of 189 km, using a non-convex 3-D shape model derived from optical lightcurves and adaptive optics images (B. Carry, private communication). On the other hand, when using the convex shape of Kaasalainen et al. (2002. Icarus 159, 369-395) in our TPM analysis, the resulting volume equivalent diameter of (41) Daphne is between 194 and 209 km, depending on the surface roughness. The shape of the asteroid is used as an a priori information in our TPM analysis. No attempt is made to adjust the shape to the data. Only the size of the asteroid and its thermal parameters (albedo, thermal inertia and roughness) are adjusted to the data. We estimated our model systematic uncertainty to be of 4% and of 7% on the determination of the asteroid volume equivalent diameter depending on whether the non-convex or the convex shape is used, respectively. In terms of thermal properties, we derived a value of the surface thermal inertia smaller than 50 J m-2 s-0.5 K-1 and preferably in the range between 0 and 30 J m-2 s-0.5 K-1. Our TPM analysis also shows that Daphne has a moderate macroscopic surface roughness.Comment: 44 pages, 8 figures, 3 table

    The Tree-Particle-Mesh N-body Gravity Solver

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    The Tree-Particle-Mesh (TPM) N-body algorithm couples the tree algorithm for directly computing forces on particles in an hierarchical grouping scheme with the extremely efficient mesh based PM structured approach. The combined TPM algorithm takes advantage of the fact that gravitational forces are linear functions of the density field. Thus one can use domain decomposition to break down the density field into many separate high density regions containing a significant fraction of the mass but residing in a very small fraction of the total volume. In each of these high density regions the gravitational potential is computed via the tree algorithm supplemented by tidal forces from the external density distribution. For the bulk of the volume, forces are computed via the PM algorithm; timesteps in this PM component are large compared to individually determined timesteps in the tree regions. Since each tree region can be treated independently, the algorithm lends itself to very efficient parallelization using message passing. We have tested the new TPM algorithm (a refinement of that originated by Xu 1995) by comparison with results from Ferrell & Bertschinger's P^3M code and find that, except in small clusters, the TPM results are at least as accurate as those obtained with the well-established P^3M algorithm, while taking significantly less computing time. Production runs of 10^9 particles indicate that the new code has great scientific potential when used with distributed computing resources.Comment: 24 pages including 9 figures, uses aaspp4.sty; revised to match published versio

    Implementing total productive maintenance in Nigerian manufacturing industries

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    Remarkable improvements have occurred recently in the maintenance management of physical assets and productive systems, so that less wastages of energy and resources occur. The requirement for optimal preventive maintenance using, for instance, justin-time (JIT) and total quality-management (TQM) techniques has given rise to whathas been called the total productive-maintenance (TPM) approach. This study explores the ways in which Nigerian manufacturing industries can implement TPM as a strategy and culture for improving its performance and suggests self-auditing and bench-marking as desirable prerequisites before TPM implementation
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