897 resultados para shadow fading


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We analyze theoretically and empirically the impact of the shadow economy on entrepreneurial entry, utilising 1998-2005 individual-level Global Entrepreneurship Monitor data merged with macro level variables. A simple correlation coefficient suggests a positive linear link between the size of the shadow economy and entrepreneurial entry. However, this masks more complex relationships. With appropriate controls and instrumenting for potential endogeneity where required, the impact of the shadow economy on entry is found to be negative, based on a linear specification. Moreover, there is also evidence of nonlinearity: entrepreneurial entry is least likely when the shadow economy is of medium size. We attribute the negative effects of shadow economy on entry to perceived strong competition faced by new entrants when the shadow economy is widespread. At the individual level, an extensive shadow economy has a more negative impact on respondents who are risk averse. In addition, in the economies where property rights are strong, the negative impact of the shadow economy is weaker.

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The objective of this paper is to explain the phenomenon of relationship fading in a business-to-consumer (B2C) context and to identify the key antecedents and drivers in this process. Fading relates to a gradual decline in consumers’ willingness to continue a relationship with a company. Therefore it may help to elucidate the ‘unexplained’ relationship dissolution and customer defection. Led by an assumption that a relationship between a consumer and a brand is like the one between individuals, the paper proposes that the trajectory of relationship fading reflects disaffection processes similar to the ones suggested in marital and romantic relationships between individuals. Stages of the fading process and their characteristics are presented. Academic and practical implications are subsequently presented.

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ACM Computing Classification System (1998): E.4, C.2.1.

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The impact of the shadow economy on entrepreneurial entry across countries is analyzed utilising 1998-2005 individual-level Global Entrepreneurship Monitor data and national macro-economic variables. A simple correlation coefficient suggests a positive relationship between the size of the shadow economy and the likelihood of entrepreneurial entry. However, this masks more complex relationships, if, as argued, the shadow economy is an embedded social phenomenon. With appropriate controls and instrumenting for potential endogeneity, the impact of the shadow economy on entry in a linear specification is found to be negative. Further, there is evidence of a U-shaped relationship: entrepreneurial entry is least likely when the shadow economy amounts to about a quarter of gross domestic product (GDP). At the individual level, an extensive shadow economy has a more negative impact on respondents who are risk averse. In addition, in the economies where property rights are stronger, the negative impact of the shadow economy is weaker. © 2012 Blackwell Publishing Ltd.

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The objective of this thesis is to develop a better understanding of the relationship fading phenomenon in business-to-consumer context. Fading relates to a gradual decline in consumer’s willingness to continue a relationship with a company. Therefore, understanding the fading process may help to elucidate the ‘unexplained’ relationship dissolution and customer defection. Led by an assumption that a relationship between a consumer and a brand is like the one between individuals, the thesis proposes that the trajectory of relationship fading reflects the disaffection processes similar to the ones suggested in marital and romantic relationships between individuals. The approach taken to answering this research question is a multi-study approach. This type of approach allows addressing each individual research question independently, using the most appropriate research methods. As a result, the thesis comprises three adjacent studies. All three studies are linked and together contribute to a better understanding of the relationship fading process, which is the main topic of the thesis. Based on the results from the first study, a set of boundary conditions of relationship fading is identified. The results of the second study suggest that predictors of relationship fading stage can be uncovered. Thirdly, different restoration techniques are explored, aiming to describe their effectiveness in various relationship fading stages. Individual objectives of the three studies are accomplished. All three studies contribute to achieving the overall objective of the thesis, namely to developing a better understanding of the phenomenon of relationship fading.

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The effects of joint hardware impairments on the performance of fixed gain amplify-and-forward (AF) relaying are studied. By considering IQ imbalance at the source and destination and the nonlinear relay the outage probability over Nakagami-m fading channels is derived, and the effects of fading and hardware impairments on the system are analysed. The analytical results are verified by Monte Carlo simulations.

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Two direct sampling correlator-type receivers for differential chaos shift keying (DCSK) communication systems under frequency non-selective fading channels are proposed. These receivers operate based on the same hardware platform with different architectures. In the first scheme, namely sum-delay-sum (SDS) receiver, the sum of all samples in a chip period is correlated with its delayed version. The correlation value obtained in each bit period is then compared with a fixed threshold to decide the binary value of recovered bit at the output. On the other hand, the second scheme, namely delay-sum-sum (DSS) receiver, calculates the correlation value of all samples with its delayed version in a chip period. The sum of correlation values in each bit period is then compared with the threshold to recover the data. The conventional DCSK transmitter, frequency non-selective Rayleigh fading channel, and two proposed receivers are mathematically modelled in discrete-time domain. The authors evaluated the bit error rate performance of the receivers by means of both theoretical analysis and numerical simulation. The performance comparison shows that the two proposed receivers can perform well under the studied channel, where the performances get better when the number of paths increases and the DSS receiver outperforms the SDS one.

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This study considers a dual-hop cognitive inter-vehicular relay-assisted communication system where all
communication links are non-line of sight ones and their fading is modelled by the double Rayleigh fading distribution.
Road-side relays (or access points) implementing the decode-and-forward relaying protocol are employed and one of
them is selected according to a predetermined policy to enable communication between vehicles. The performance of
the considered cognitive cooperative system is investigated for Kth best partial and full relay selection (RS) as well as
for two distinct fading scenarios. In the first scenario, all channels are double Rayleigh distributed. In the second
scenario, only the secondary source to relay and relay to destination channels are considered to be subject to double
Rayleigh fading whereas, channels between the secondary transmitters and the primary user are modelled by the
Rayleigh distribution. Exact and approximate expressions for the outage probability performance for all considered RS
policies and fading scenarios are presented. In addition to the analytical results, complementary computer simulated
performance evaluation results have been obtained by means of Monte Carlo simulations. The perfect match between
these two sets of results has verified the accuracy of the proposed mathematical analysis.

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There is a public perception that politicians in the United Kingdom are increasingly detached from the electorate due to the apparent increase in the number of ‘career politicians’ with a professional background in politics. This article examines the occupational backgrounds of successful candidates to the House of Commons of the United Kingdom between the 1997 and 2010 general elections, comparing the parliamentary compositions of the three main political parties (Conservatives, Labour and Liberal Democrats) during this period, and the Cabinet and Shadow Cabinet as of 2014. By evaluating original and secondary quantitative data, it is argued that professionalised politicians have increased in the House of Commons relative to other occupational backgrounds, and are even further disproportionately represented in the senior teams of each major party.

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Multiuser selection scheduling concept has been recently proposed in the literature in order to increase the multiuser diversity gain and overcome the significant feedback requirements for the opportunistic scheduling schemes. The main idea is that reducing the feedback overhead saves per-user power that could potentially be added for the data transmission. In this work, the authors propose to integrate the principle of multiuser selection and the proportional fair scheduling scheme. This is aimed especially at power-limited, multi-device systems in non-identically distributed fading channels. For the performance analysis, they derive closed-form expressions for the outage probabilities and the average system rate of the delay-sensitive and the delay-tolerant systems, respectively, and compare them with the full feedback multiuser diversity schemes. The discrete rate region is analytically presented, where the maximum average system rate can be obtained by properly choosing the number of partial devices. They optimise jointly the number of partial devices and the per-device power saving in order to maximise the average system rate under the power requirement. Through the authors’ results, they finally demonstrate that the proposed scheme leveraging the saved feedback power to add for the data transmission can outperform the full feedback multiuser diversity, in non-identical Rayleigh fading of devices’ channels.

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In this paper, we consider the transmission of confidential information over a κ-μ fading channel in the presence of an eavesdropper who also experiences κ-μ fading. In particular, we obtain novel analytical solutions for the probability of strictly positive secrecy capacity (SPSC) and a lower bound of secure outage probability (SOPL) for independent and non-identically distributed channel coefficients without parameter constraints. We also provide a closed-form expression for the probability of SPSC when the μ parameter is assumed to take positive integer values. Monte-Carlo simulations are performed to verify the derived results. The versatility of the κ-μ fading model means that the results presented in this paper can be used to determine the probability of SPSC and SOPL for a large number of other fading scenarios, such as Rayleigh, Rice (Nakagamin), Nakagami-m, One-Sided Gaussian, and mixtures of these common fading models. In addition, due to the duality of the analysis of secrecy capacity and co-channel interference (CCI), the results presented here will have immediate applicability in the analysis of outage probability in wireless systems affected by CCI and background noise (BN). To demonstrate the efficacy of the novel formulations proposed here, we use the derived equations to provide a useful insight into the probability of SPSC and SOPL for a range of emerging wireless applications, such as cellular device-to-device, peer-to-peer, vehicle-to-vehicle, and body centric communications using data obtained from real channel measurements.