1,721,770 research outputs found
SME internationalisation and Its impact on firm performance
Full text linkThe book examines various contemporary international business issues from various viewpoints, draws on research conducted in different countries, examines IB issues in both developed and emerging country contexts, offers various theoretical ..
A linearized implicit pseudo-spectral method for some model equations: the regularized long wave equations
No full textAn efficient numerical method is developed for the numerical solution of non-linear wave equations typified by the regularized long wave equation (RLW) and its generalization (GRLW). The method developed uses a pseudo-spectral (Fourier transform) treatment of the space dependence together with a linearized implicit scheme in time. An important advantage to be gained from the use of this method, is the ability to vary the mesh length, thereby reducing the computational time. Using a linearized stability analysis, it is shown that the proposed method is unconditionally stable. The method is second order in time and all-order in space. The method presented here is for the RLW equation and its generalized form, but it can be implemented to a broad class of non-linear long wave equations, with obvious changes in the various formulae. Test problems, including the simulation of a single soliton and interaction of solitary waves, are used to validate the method, which is found to be accurate and efficient. The three invariants of the motion are evaluated to determine the conservation properties of the algorithm
A Wideband and Polarization-insensitive Switchable Absorber/Reflector with Simple Biasing Configuration
No full textIn this paper, a multifunctional switchable absorber/reflector with wideband and polarization-insensitive characteristics is presented. PIN diodes are employed to help realize the multifunctional characteristics, and the bias networks for biasing them are integrated with the frequency selective surface (FSS) elements, which reduces the adverse impact of additional bias lines. A super-element based on four basic structures are developed to realize the active control and the polarization-insensitivity simultaneously. Compared to the switchable designs previously reported, the proposed structure has the advantage of possessing multiple real-time and switchable operating states (i.e. dual-poalrizaed absorption, dual-polarized reflection, TE absorption/TM reflection and TE reflection/TM absorption), and meanwhile, attaining a much wider switchable bandwidth
Credit markets, relationship lending, and the dynamics of firm entry
No full textWe study the impact of credit relationships on firm entry, and the implications for aggregate investment and output. Exploiting Italian data, we find that relationship-oriented local credit markets feature fewer, larger entrants, and relatively more spinoff entrants. Relationship lending discourages de novo entry when banks’ knowledge is incumbent-specific but promotes knowledge transfers to spinoffs. We explain these patterns in a dynamic general equilibrium model where banks accumulate information in credit relationships and can reuse information when financing entrants. Relationship lending raises output, as the larger investments and the credit reallocation from de novos to spinoffs outweigh the entry slowdown
A Switchable Transmission/ Absorption/Reflection Frequency Selective Surface
No full textIn this paper, a novel polarization-insensitive frequency selective surface (FSS) design realizing the switching between the three functions of transmission/absorption/reflection is presented. The proposed structure consists of two active frequency selective surfaces (AFSSs) printed on different dielectric substrates and separated by an air spacer. By controlling the status of the PIN diodes between the upper and lower AFSS structures, three different electromagnetic functions of transmission/absorption/reflection are realized. In addition, the proposed solution achieves a valid oblique incident angle and dual- polarization characteristics
A switchable and tunable multifunctional absorber/reflector with polarization-insensitive features
No full textA switchable and tunable multifunctional absorber/reflector with polarization-insensitive performance is designed. The proposed structure comprises a switchable screen on the top layer, a tunable screen on the bottom layer and an air spacer in between. PIN diodes are employed in the switchable structure to provide multiple switchable states (dual-polarized absorber, dual-polarized reflector, TE/TM wave absorber/reflector and TM/TE wave absorber reflector) by actively controlling the feeding modes between “11” and “00” states. Tunable capability, are instead guaranteed by the tunable screen loaded with varactor diodes. The polarization insensitivity is guaranteed by constructing a super element, which is a combination of four similar unitary elements. To mitigate the adverse influence of the dedicated feed lines, independent coplanar and back feeding modes are configured to provide biases for PIN diodes and varactor diodes, respectively. Finally, a prototype of the proposed structure is fabricated and measured in a microwave anechoic chamber, and the measured results demonstrate both the switchable and tunable characteristics of the proposed multifunctional absorber/reflector
Active frequency selective surface with two independent electromagnetic functions
No full textIn this paper., we present a novel active frequency selective surface (AFSS) with two independent functions. The function of frequency tuning for TM polarization and the function of electromagnetic switching for TE polarization can be achieved by controlling the varactor diodes and PIN diodes loaded on the top- and bottom-layer., respectively. A parallel feeding pattern is employed to reduce the negative impact of the bias network., which also guarantees the working reliability of the structure under damages of active devices and decreases the bias voltage for the components., especially for varactor diodes. In addition., equivalent circuit models for the AFSS have been constructed to analyze the working principle of the structure and verify the simulation results from the HFSS software
A quasi-elliptical bandpass frequency selective surface with low-profile and miniaturization characteristics
No full textA low-profile and miniaturized frequency selective surface (FSS) with dual-polarized bandpass characteristics is proposed in this article. The FSS is a second-order structure with two layers separated by an air spacer, achieving two transmission poles (TPs) and two transmission zeros (TZs) at both sides of the TPs. Using the miniaturized structure, the physical dimension of the element is reduced to 0.09λ × 0.09λ, where λ is the free-space wavelength at the center frequency. Thus, the structure exhibits stable performance with respect to different incident angles. The overall thickness is 0.053λ, which is much thinner than alternative second-order FSSs using the traditional cascading technique. This feature makes it a candidate to be applied in low frequency bands with long wavelengths. In addition, the operating principle of the proposed structure is analyzed by using the equivalent circuit method (ECM) and the surface current distribution is also given. Finally, a prototype is fabricated and measured to validate the simulated results
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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