29,921 research outputs found
RF environment survey of Space Shuttle related EEE frequency bands
Radio frequency assignments within the continental United States in frequency bands between 121 MHz abd 65 GHz were surveyed and analyzed in order to determine current utilization of anticipated frequency bands for the shuttle borne electromagnetic environment experiment. Data from both government and nongovernment files were used. Results are presented in both narrative form and in histograms which show the total number of unclassified assignments versus frequency and total assigned power versus frequency
The electronics industry in central and eastern Europe: an emerging production location in the alignment of networks perspective
This paper analyses the emergence of central Europe as a new location for the production of electronics. The main factors that drive integration in the region into global production networks are also analysed, as well as prospects for upgrading the industry by using network alignment perspectives.
Foreign investment is the primary vehicle of integration of CEE electronics firms into global production networks, and Hungary has moved furthest along this path, positioning itself as a major low-cost supply base in the region. Czech and Polish electronics industries are connected, in smaller, but increasing, degrees to international electronics production networks. Networks that are being built in CEE in electronics are usually confined to subsidiaries with still limited local subcontracting; they are export-oriented and are expanding.
Local subsidiaries have mastered production capabilities and several subsidiaries in Hungary are European mandate suppliers in their respective lines of business. EU demand is the main pull factor, which gives cohesion to the actions of MNCs as well as to the action of local and national governments in CEE. The layer of local firms is still very weak with very limited capabilities in core technologies. This is the key weakness which prevents further alignment of networks in CEE electronics. Local governments play an important role in working jointly with foreign investors in establishing industrial parks and new capacities
Hybrid Satellite-Terrestrial Communication Networks for the Maritime Internet of Things: Key Technologies, Opportunities, and Challenges
With the rapid development of marine activities, there has been an increasing
number of maritime mobile terminals, as well as a growing demand for high-speed
and ultra-reliable maritime communications to keep them connected.
Traditionally, the maritime Internet of Things (IoT) is enabled by maritime
satellites. However, satellites are seriously restricted by their high latency
and relatively low data rate. As an alternative, shore & island-based base
stations (BSs) can be built to extend the coverage of terrestrial networks
using fourth-generation (4G), fifth-generation (5G), and beyond 5G services.
Unmanned aerial vehicles can also be exploited to serve as aerial maritime BSs.
Despite of all these approaches, there are still open issues for an efficient
maritime communication network (MCN). For example, due to the complicated
electromagnetic propagation environment, the limited geometrically available BS
sites, and rigorous service demands from mission-critical applications,
conventional communication and networking theories and methods should be
tailored for maritime scenarios. Towards this end, we provide a survey on the
demand for maritime communications, the state-of-the-art MCNs, and key
technologies for enhancing transmission efficiency, extending network coverage,
and provisioning maritime-specific services. Future challenges in developing an
environment-aware, service-driven, and integrated satellite-air-ground MCN to
be smart enough to utilize external auxiliary information, e.g., sea state and
atmosphere conditions, are also discussed
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