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21.
This paper presents an improved attendance control system, required for continuous evaluation which has become compulsory following the Bologna Process. It provides a solution based on NFC technology and is based on a real project developed and pilot tested at the “Universidad Pontificia de Salamanca, Campus Madrid”.  相似文献   
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Local governments are responsible for the supply of important public services in cities. On many occasions the management of those services is externalized. There is extensive literature analyzing the explanations for the governance option taken by local governments, aiming to ascertain the reasons why the management of certain services is externalized. Recent research has highlighted the fact that time has not been contemplated by research dealing with explanatory factors in the decision to contract out municipal services. This is a key issue in order to identify the real reason behind policymakers’ decisions about the management of the services in cities. This paper tests the importance of taking into account time in the research into contracting out. This is undertaken by means of two methodological tests in the design of variables from a dataset containing 744 municipalities in Southern Spain. Using this empirical analysis as a basis, it is concluded that considering time contributes towards enhancing the specification of the model and that omitting this aspect could lead to misunderstanding the motivation behind such decisions.  相似文献   
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This work analyzes the effects of the regulation/deregulation processes carried out on the evolution of efficiency in Spanish retail-sector firms in the period 1996–2004. The results suggest that the regulation in this sector has had a considerable influence on firms’ efficiency, in particular, the legislation on the expansion of commercial opening hours after 2000. The results provide clear evidence of a convergence in firms’ efficiency from the initial year considered to superior levels. Moreover, the pattern of convergence differs in function of the region in which the firm operates. The evolution of efficiency given by the means of different groups of regulation intensity levels through the time seems to show clearly in the groups of high and low regulation. It is observed that the group of high regulation is the most efficient. The analysis of the firms as a whole confirms the convergence process. Considering the analysis for subperiods an improvement is observed for all regions in the period 2000 at 2004.  相似文献   
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Wireless Networks - This paper presents a structural equation model that relates knowledge coordination with access to information in the process of implementing Six Sigma and their impact on the...  相似文献   
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The design of standard communications and security mechanisms for resource‐constrained sensing applications and devices may provide an important contribution for its integration with the Internet and consequently towards the realization of what we nowadays identify as the Internet of Things. This vision will only be realizable if appropriate security mechanisms are available, and in this context we target the design and experimental evaluation of security mechanisms for communications at the network‐layer with sensing devices (smart objects) using the standard IPv6 protocol. Our work proposes and evaluates the usage of new compressed security headers for the network layer with smart objects. We implement and evaluate what is, as far as we know, the first proposal of security at the network layer experimentally evaluated using the TinyOS operating system and its networking stack. As we verify in the course of our evaluation study, various scenarios employing network‐layer secure communications involving smart objects are feasible, particularly when security mechanisms are designed to benefit from cross‐layer interactions that allow the optimization of expensive cryptographic operations. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
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The use of non-toxic and low-cost vitamins like α-tocopherol (α-TCP, vitamin E) to improve the photophysical properties and stability of perovskite nanocrystals (PNCs), through post-synthetic ligand surface passivation, is demonstrated for the first time. Especially interesting is its effect on CsPbI3 the most unstable inorganic PNC. Adding α-TCP produces that the photoluminescence quantum yield (PLQY) of freshly prepared and aged PNCs achieves values of ≈98% and 100%, respectively. After storing 2 months under ambient air and 60% relative humidity, PLQY is maintained at 85% and 67%, respectively. α-TCP restores the PL features of aged CsPbI3 PNCs, and mediates the radiative recombination channels by reducing surface defects. In addition, the combination of α-TCP and PNCs facilitates the chemical formulation to prepare PNCs-acrylic polymer composites processable by additive manufacturing. This enables the development of complex shaped parts with improved luminescent features and long-term stability for 4 months, which is not possible for non-modified PNCs. A PLQY ≈92% is reached in the 3D printed polymer/PNC composite, the highest value obtained for a red-emitting composite solid until now as far as it is known. The passivation shell provided by α-TCP makes that PNCs inks do not suffer any degradation process avoiding the contact with the environment and preserve their properties after reacting with polar monomers during composite polymerization.  相似文献   
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A master-slave D-type flip-flop (MS DFF) fabricated in a self-aligned InP DHBT technology is presented. The packaged circuit shows full-rate clock operation at 48 Gbit/s. Very low time jitter and good retiming capabilities are observed. Layout aspects, packaging and measurement issues are discussed in particular  相似文献   
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Convolutional tailbiting codes are widely used in mobile systems to perform error-correcting strategies of data and control information. Unlike zero tail codes, tailbiting codes do not reset the encoder memory at the end of each data block, improving the code efficiency for short block lengths. The objective of this work is to propose a low-complexity maximum likelihood decoding algorithm for convolutional tailbiting codes based on the Viterbi algorithm. The performance of the proposed solution is compared to that of another maximum likelihood decoding strategy which is based on the A* algorithm. The computational load and the memory requirements of both algorithms are also analysed in order to perform a fair comparison between them. Numerical results considering realistic transmission conditions show the lower memory requirements of the proposed solution, which makes its implementation more suitable for devices with limited resources.  相似文献   
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