83,479 research outputs found

    A joint-channel diagonalization for multiuser MIMO antenna systems

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    In this paper, we address the problem of improving the performance of multiuser space-division multiplexing (SDM) systems where multiple independent signal streams can be transmitted in the same frequency and time slot. The problem is important in multiuser multiple-input multiple-output systems where communication from one base station to many mobile stations can occur simultaneously. Our objective is to devise a multiuser linear space-time precoder for simultaneous channel diagonalization of the multiuser channels enabling SDM. Our new approach is based on diagonalizing the multiuser channel matrices and we use a variation of successive Jacobi rotations. In addition to the diagonalization, our approach attempts to optimize the resultant channel gains for performance enhancement. Our method is valid for both frequency-flat and frequency-selective fading channels but we assume that the base station knows all the channels and that they are quasi-stationary

    Establishing a Hybrid Wound and Ostomy Continuing Education Program

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    Wound and ostomy nurses receive specialty training and certification to provide care in abdominal stomas, ostomies, wounds, fistulas, and pressure injuries. The eight existing nationwide programs in 2011 were inadequate to meet increasing patient population demands. We developed an innovative nondegree, postbaccalaureate continuing wound and ostomy education program using a hybrid design. The program integrated interactive online classes with intensive onsite classes and skills training. The program has been granted seven-year accreditation; student evaluations have been positive

    Antipersistant Effects in the Dynamics of a Competing Population

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    We consider a population of agents competing for finite resources using strategies based on two channels of signals. The model is applicable to financial markets, ecosystems and computer networks. We find that the dynamics of the system is determined by the correlation between the two channels. In particular, occasional mismatches of the signals induce a series of transitions among numerous attractors. Surprisingly, in contrast to the effects of noises on dynamical systems normally resulting in a large number of attractors, the number of attractors due to the mismatched signals remains finite. Both simulations and analyses show that this can be explained by the antipersistent nature of the dynamics. Antipersistence refers to the response of the system to a given signal being opposite to that of the signal's previous occurrence, and is a consequence of the competition of the agents to make minority decisions. Thus, it is essential for stabilizing the dynamical systems.Comment: 4 pages, 6 figure

    On finite complete rewriting systems and large subsemigroups

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    Let SS be a semigroup and TT be a subsemigroup of finite index in SS (that is, the set STS\setminus T is finite). The subsemigroup TT is also called a large subsemigroup of SS. It is well known that if TT has a finite complete rewriting system then so does SS. In this paper, we will prove the converse, that is, if SS has a finite complete rewriting system then so does TT. Our proof is purely combinatorial and also constructive.Comment: We have made major changes to the paper and simplified most of the proof

    Treatment of control data in lunar phototriangulation

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    In lunar phototriangulation, there is a complete lack of accurate ground control points. The accuracy analysis of the results of lunar phototriangulation must, therefore, be completely dependent on statistical procedure. It was the objective of this investigation to examine the validity of the commonly used statistical procedures, and to develop both mathematical techniques and computer softwares for evaluating (1) the accuracy of lunar phototriangulation; (2) the contribution of the different types of photo support data on the accuracy of lunar phototriangulation; (3) accuracy of absolute orientation as a function of the accuracy and distribution of both the ground and model points; and (4) the relative slope accuracy between any triangulated pass points

    Twisted Alexander invariants of complex hypersurface complements

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    The Benefit Function Approach to Modeling Price-Dependent Demand Systems: An Application of Duality Theory

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    In this article we advocate more extensive use of the benefit function in specifying price-dependent or inverse demand models. In particular, we demonstrate how duality theory may be used to establish the inter-relationships between the Marshallian (or Hicksian) inverse demands and Luenberger's adjusted price functions, allowing estimable inverse demands to be derived directly from a benefit function. We also make use of a numerical inversion estimation method to rectify the "unobservability of utility problem" encountered in the empirical analysis of these inverse demands. To illustrate the usefulness of the proposed methods, we estimate two systems of inverse demands for Japanese quarterly fish consumption. Results generally indicate that the proposed methods are promising and operationally feasible so that we have opened up a wider range of empirical inverse demand specifications that can be subjected to tight theoretical restrictions.Benefit Functions; Duality Theory; Numerical Inversion Estimation Method

    Palm oil refinery wastes treatment

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    Effluent from the refining of crude palm oil was subjected to physical-chemical and biological treatment. An inclined corrugated parallel plates oil separator spaced at 25 mm was used with hydraulic loading rates ofO.2. 0.5 and I m³ mol_h. 91% oil and grease removal could be achieved at 0.2 m³ m–2 _h. Coagulation and flocculation carried out on batch samples after oil and grease separation revealed that with 100 mg 1- I alum addition BOO was reduced from 3500 to 450 mg 1–1 and COD from 8600 to 750 mg 1–1 after 30 min settling. Higher doses of alum and doses of polyelectrolyte, activated carbon and sodium hypochloride did not yield significant additional reductions in BOD and COD. Batch dissolved air flotation (OAF) removed 90% of the suspended solids with 2.7% solids in the thickened sludge at an A/S ratio of 0.014. This method yielded the similar effluent quality as the inclined corrugated plates oil and grease separator. Field data from a OAF plant compare closely with data achieved in this study. Activated sludge treatment on the effluent from the oil separator yielded a BOD of 46 mg I–1 with a loading rate of OJ g BOD (g MLVSS) –1 day. Total dissolved solids (TDS) remained high and removal through coagulation and chemical oxidation brought the COD level down to around I80mg I–1 Biokinetic coefficients Y. lid' K and K, were found to be 0.S5 g VSS (g BOD) –1. 0.016day–1. 0.12 g BOD (g VSS) –1 <day and 510 mg 1–1 BOD respectively
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