| 1. |
- Andersson, Martin, et al.
(författare)
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Acquisitions of start-ups by incumbent businesses A market selection process of "high-quality" entrants?
- 2016
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Ingår i: Research Policy. - : Elsevier BV. - 0048-7333 .- 1873-7625. ; 45:1, s. 272-290
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Tidskriftsartikel (refereegranskat)abstract
- We analyze the frequency and nature by which new firms are acquired by established businesses. Acquisitions are often considered to reflect a technology transfer process and to also constitute one way in which a "symbiosis" between new technology-based firms (NTBFs) and established businesses is realized. Using a micro-level dataset for Sweden in which we follow new entrants up to 18 years after entry, we show that acquisitions of recent start-ups are rare and restricted to a small group of entrants with defining characteristics. Estimates from competing risks models show that acquired start-ups, in particular by multinational enterprises (MNEs), stand out from entrants that either remain independent or exit by being much more likely to be spin-offs operating in high-tech sectors, having strong technological competence, and having weak internal financial resources. Our overall findings support the argument that acquisitions primarily concern NTBFs in market contexts where entry costs are large, access to finance is important and incumbents have valuable complementary capabilities and resources. (C) 2015 Elsevier B.V. All rights reserved.
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| 2. |
- Bennin, Kwabena Ebo, 1987-, et al.
(författare)
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Revisiting the Impact of Concept Drift on Just-in-Time Quality Assurance
- 2020
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Ingår i: Proceedings - 2020 IEEE 20th International Conference on Software Quality, Reliability, and Security, QRS 2020. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728189130 ; , s. 53-59
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Konferensbidrag (refereegranskat)abstract
- The performance of software defect prediction(SDP) models is known to be dependent on the datasets used for training the models. Evolving data in a dynamic software development environment such as significant refactoring and organizational changes introduces new concept to the prediction model, thus making improved classification performance difficult. In this study, we investigate and assess the existence and impact of concept drift on SDP performances. We empirically asses the prediction performance of five models by conducting cross-version experiments using fifty-five releases of five open-source projects. Prediction performance fluctuated as the training datasets changed over time. Our results indicate that the quality and the reliability of defect prediction models fluctuate over time and that this instability should be considered by software quality teams when using historical datasets. The performance of a static predictor constructed with data from historical versions may degrade over time due to the challenges posed by concept drift. © 2020 IEEE.
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| 3. |
- Grbic, Nedelko, et al.
(författare)
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Blind signal separation using overcomplete subband representation
- 2001
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Ingår i: IEEE transactions on speech and audio processing. - : IEEE. - 1063-6676 .- 1558-2353. ; 9:5, s. 524-533
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Tidskriftsartikel (refereegranskat)abstract
- This paper discusses a multirate filterbank-based extended infomax algorithm for real-world signal separation, i.e., convolved mixtures separation. Since convolution in the time domain corresponds to instantaneous mixing in the frequency domain, polyphase subband projection naturally becomes an efficient alternative to the Fourier transform based frequency domain approach. The online implementation proposed is featured by a simultaneous inverse channel identification in the frequency domain and signal filtering in the time domain. It is shown that an over-representation structure reduces aliasing between different bands and results in more accurate inverse channel estimates. Therefore, it provides better performance than the Fourier transform based structure in the measures of both separation and distortion. The performance limitation of the method is also evaluated in terms of the Wiener solution.
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| 4. |
- Grbic, Nedelko, et al.
(författare)
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Performance Improvement of Multiple Array 3D Sonic Digitizer System via Calibration
- 1999
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Konferensbidrag (refereegranskat)abstract
- Multiple array 3D sonic digitizer system is a product made for measuring the geometric structure of an arbitrary object in three dimension. This paper gives a theoretical performance evaluation of the system. The Cramer-Rao Lower Bound of the parameter estimates of a linear segment is derived. In addition, the distortion effect caused by the time-delay bias, including rescaling, rotation and bending of the original object, is clarified. A simple method using a line segment is proposed to calibrate the bias term arised in the different parts of the system. Finally a simulation gives a numerical demonstration of the previous analysis and performance improvement of the suggested method.
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| 5. |
- Li, Cheng-Wang, et al.
(författare)
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Comparison of mechanical properties of various joining processes of aluminum-titanium light alloy
- 2023
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Ingår i: Suxing Gongcheng Xuebao/Journal of Plasticity Engineering. - : Beijing Res. Inst. of Mechanical and Elec. Technology. - 1007-2012. ; 30:8, s. 138-145
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Tidskriftsartikel (refereegranskat)abstract
- 5A06 aluminum alloy and TA1 titanium alloy were selected for the connection tests of flow drill screw, ultrasonic clinch and ultrasonic self-piercing riveting. The influence of plate overlap methods on mechanical properties of each group of joints was studied by static tensile tests. The results show that the mechanical properties of the flow drill screw joints and the ultrasonic self-piercing riveted joints are significantly improved when the soft plate is on top during the riveting process. The plate overlap method has little effect on the ultrasonic clinch joint. Flow drill screw joints have the best cushioning and shock absorption performance, but the stability is poor, and it is more limited when applied to body structures. Ultrasonic clinch joints have low cost and simple process, but poor shear resistance and are not suitable for body structures subjected to high stress. Compared with the other two connection methods, the ultrasonic self-piercing riveted connection has the best stability, the best tensile resistance and shear stiffness, and is suitable for much of the structure in lightweight field of automobile body. © 2023 Beijing Res. Inst. of Mechanical and Elec. Technology. All rights reserved.
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| 6. |
- Tao, Xiao-Jiao, et al.
(författare)
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Behind Acoustic Doppler Current Profiler : Narrowband Volume Backscattering Signal Model, Analysis and Estimation
- 1999
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report examines the statistical properties of the narrowband Doppler volume backscattering process and discusses its spectral centroid estimation problem. After clarifying the mechanism of both the finite duration Doppler effect and the continuously space-shifted integration process, the first two order time-varying statistics under a more general assumption, i.e. von Mises distribution, of random phase are derived. The generalization permits nonuniform phase tendency, which occurs in layered medium scattering. Based on the locally stationary process model, the evolutionary spectrum of the signal is derived where the variation of the backscattering strength enters as an amplitude modulation. On the contrary, the variation of the random phase distribution acts as both the amplitude modulation and the frequency modulation. The observability and the estimation of the average flow speed are discussed. It is shown that even under the homogeneous condition, the spectral centroid does not coincide with the aver age flow speed. Finally, a semiparametric spectral centroid estimation method, which simply contains an AR(2) model with its time-varying coefficients adapted by a wavelet shrinkage is proposed.
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| 7. |
- Tao, Xiao-Jiao, et al.
(författare)
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Narrowband acoustic doppler volume backscattering signal-part I : evolutionary spectral analysis
- 2002
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Ingår i: IEEE Transactions on Signal Processing. - 1053-587X .- 1941-0476. ; 50:11, s. 2644-2655
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Tidskriftsartikel (refereegranskat)abstract
- This paper examines the statistical properties of the narrowband Doppler volume backscattering process and analyzes its evolutionary spectrum. After clarifying the mechanism of both the finite duration Doppler effect and the continuously space-shifted integration process, the first two order time-varying statistics under a more general assumption, i.e., von Mises distribution, of random phase are derived. The generalization permits nonuniform phase tendency, which occurs in layered medium scattering. Based on the locally stationary process model, the evolutionary spectrum of the signal is derived. It is shown that the variation of the backscattering strength enters the spectrum as an amplitude modulation, whereas the variation of the random phase distribution acts as both the amplitude modulation and the frequency modulation. Finally, the observability of the average flow speed using spectral centroid estimate is discussed.
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| 8. |
- Tao, Xiao-Jiao, et al.
(författare)
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Narrowband acoustic doppler volume backscattering signal-part II : spectral centroid estimation
- 2002
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Ingår i: IEEE Transactions on Signal Processing. - : IEEE. - 1053-587X .- 1941-0476. ; 50:10, s. 2656-2660
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a novel algorithm to estimate the time-varying spectral centroid of the narrowband Doppler volume backscattering signal. It is constructed in a semi-parametric way, that is, modeling parametrically the local narrowband evolutionary spectrum using an AR(2) and nonparametrically adapting its time-varying coefficients using the wavelet shrinkage. The improved performance is gained by the underlying linear prediction function of the AR(2) and the minimax optimality of the unknown smoothness adaptation of the wavelet shrinkage procedure.
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| 9. |
- Wu, Zhe, et al.
(författare)
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A wide-band all-metal and high-gain omnidirectional antenna with simple prototype
- 2022
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Ingår i: International Journal of RF and Microwave Computer-Aided Engineering. - : WILEY. - 1096-4290 .- 1099-047X. ; 32:1
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Tidskriftsartikel (refereegranskat)abstract
- An all-metal dipole two-element array antenna is proposed to achieve a wide-band impedance bandwidth and an omnidirectional radiation pattern. The concept of this antenna derives from a quarter-shorted magnetic dipole structure. The proposed antenna consists of an air-filled metallic parallel bi-plate and two dipole elements. The dipole elements are perpendicularly fabricated at the open end of the bi-plate. Fed by a single coaxial SMA connector in the center of this structure, a quasi-TEM mode in the bi-plate can be excited similar to the parallel waveguide. Based on the multiple resonances and line-array effect, the proposed antenna can achieve a wide-band working bandwidth and a stable omnidirectional pattern. Simulated and experimental results confirm that this antenna has a peak gain of 4.16 dBi and a relative impedance bandwidth of 72% (0.8-1.7 GHz). The proposed antenna can be used in UAV (unmanned aerial vehicle) application.
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| 10. |
- Xiao, Jing, et al.
(författare)
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Industrial Diversification in Europe : The Differentiated Role of Relatedness
- 2018
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Ingår i: Economic Geography. - : TAYLOR & FRANCIS LTD. - 0013-0095 .- 1944-8287. ; 94:5, s. 514-549
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Tidskriftsartikel (refereegranskat)abstract
- There is increasing interest in the drivers of industrial diversification, and how these depend on economic and industry structures. This article contributes to this line of inquiry by analyzing the role of industry relatedness in explaining variations in industry diversification, measured as the entry of new industry specializations, across 173 European regions during the period 2004-2012. First, we show that there are significant differences across regions in Europe in terms of industrial diversification. Second, we provide robust evidence showing that the probability that a new industry specialization develops in a region is positively associated with the new industry's relatedness to the region's current industries. Third, a novel finding is that the influence of relatedness on the probability of new industrial specializations depends on innovation capacity of a region. We find that relatedness is a more important driver of diversification in regions with a weaker innovation capacity. The effect of relatedness appears to decrease monotonically as the innovation capacity of a regional economy increases. This is consistent with the argument that high innovation capacity allows an economy to break from its past and to develop, for the economy, truly new industry specializations. We infer from this that innovation capacity is a critical factor for economic resilience and diversification capacity.
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