Practical constraints on network architecture and signalling in the MSAT system

Telesat Mobile Inc. plans to provide mobile satellite communications services in Canada in 1993/4, in close cooperation with the American Mobile Satellite Consortium Inc., which will be providing services in the U.S.A. L-band frequencies will be used in multiple beams for communication with mobile terminals. Ku-band frequencies will be used for the feeder-links to fixed stations. The system will support voice and data communications. The baseline Canadian system will support approximately 450 assignable voice channels, some fraction of which will be the equivalent in data channels. The method of multiple access will be Frequency Division Multiple Access/Single Channel Per Carrier. The availability of frequencies, the availability of technology and the time scale for implementation all constrain the network architecture for the system. Further, it is important to have an open specification to encourage multiple equipment vendors. The interplay of these constraints is discussed

The state of the responsible research and innovation programme: A case for its application in additive manufacturing

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Many of the ethical issues of additive manufacturing (AM) are not well known or understood, and there remains a policy vacuum that needs to be addressed. This paper aims to describe an approach that has been applied successfully to other emerging technologies, referred to as the responsible research and innovation (RRI) framework programme. A case is then made for the application of this approach in the AM industry with an illustration of how it might be used

The Role of State Trading Enterprises and Their Impact on Agricultural Development and Economic Growth in Developing Countries

The role of state trading enterprises (STEs) is significant for international trade, especially since the Uruguay Round. They account for large shares of world trade in certain products: about 40 percent for wheat and 30 percent for dairy products (WTO, 2000). This article examines the influence of STEs on the development of the agricultural sector in developing countries. During both the Uruguay Round and Doha Round negotiations, there have been serious complaints from developing countries that the operation of STEs is trade distorting and creates serious obstacles to agricultural development.International Relations/Trade,

Fixed-rank Rayleigh Quotient Maximization by an MMPSK Sequence

Certain optimization problems in communication systems, such as limited-feedback constant-envelope beamforming or noncoherent $M$-ary phase-shift keying ($M$PSK) sequence detection, result in the maximization of a fixed-rank positive semidefinite quadratic form over the $M$PSK alphabet. This form is a special case of the Rayleigh quotient of a matrix and, in general, its maximization by an $M$PSK sequence is $\mathcal{NP}$-hard. However, if the rank of the matrix is not a function of its size, then the optimal solution can be computed with polynomial complexity in the matrix size. In this work, we develop a new technique to efficiently solve this problem by utilizing auxiliary continuous-valued angles and partitioning the resulting continuous space of solutions into a polynomial-size set of regions, each of which corresponds to a distinct $M$PSK sequence. The sequence that maximizes the Rayleigh quotient is shown to belong to this polynomial-size set of sequences, thus efficiently reducing the size of the feasible set from exponential to polynomial. Based on this analysis, we also develop an algorithm that constructs this set in polynomial time and show that it is fully parallelizable, memory efficient, and rank scalable. The proposed algorithm compares favorably with other solvers for this problem that have appeared recently in the literature.Comment: 15 pages, 12 figures, To appear in IEEE Transactions on Communication

Whirl and Stall Flutter Simulation Using CFD

This paper presents recent research on numerical methods for whirl and stall flutter using computational fluid dynamics. The method involves coupling of the HMB3 CFD solver of the University of Glasgow and a NASTRAN derived structural model. Based upon a literature survey, a significant amount of research has been conducted on the numerical investigation of tiltrotors, with a focus on the XV-15 and V-22 aircraft. Within this paper, the coupling procedure is presented along with a steady CFD computation to highlight the accuracy of the high-fidelity method. In addition to this, a simple method is used to investigate the whirl flutter boundary of a standard propeller and the XV-15 blade

Locating Decision Rights: Evidence from the Mutual Fund Industry

Mutual fund advisors make portfolio decisions for their funds on a daily basis. We examine the location of these portfolio decision rights on two dimensions. First, we consider the geographic location of the decision rights. Second, we consider whether the decision rights remain with an advisor or are allocated to an independent sub-advisor. We argue that the allocation of portfolio decision rights involves a tradeoff between the opportunity cost of not matching decision rights with specific knowledge, and the agency costs associated with moving the decision rights to the specific knowledge. The patterns in the location of decision rights are consistent with the tradeoff being a meaningful determinant of the allocation of decision rights in the mutual fund industry. We also find that funds that are predicted to be sub-advised and are sub-advised outperform those that are predicted to be sub-advised but are not