A Millimeter Wave MIMO Testbed for 5G Communications

This paper presents a 2 x 2 millimeter wave (mm-wave) multiple-input-multiple-output (MIMO) testbed that operates at around 30 GHz. The link assessment of the system operating at 26.25 GHz was carried out on a test bench, with a short communication distance between the transmitting and receiving antennas. A user-programmable, reconfigurable and real-time signal processing field-programmable gate arrays (FPGAs)-based software defined radio (SDR) system was employed as part of the testbed to validate the system-level performance for a downlink time division long-term evolution (TD-LTE) duplex scheme. Constellation diagram for quadrature phase shift keying (QPSK) digital modulation were acquired while the testbed was operating at 30 GHz. The testbed could be employed for the development of signal test, communication algorithm and measurement metrology for 5G communications.Comment: 89th ARFTG Microwave Measurement Conference (ARFTG 2017

Microcanonical rates from ring-polymer molecular dynamics: Direct-shooting, stationary-phase, and maximum-entropy approaches

We address the calculation of microcanonical reaction rates for processes involving significant nuclear quantum effects using ring-polymer molecular dynamics (RPMD), both with and without electronically non-adiabatic transitions. After illustrating the shortcomings of the naive free-particle direct-shooting method, in which the temperature of the internal ring-polymer modes is set to the translational energy scale, we investigate alternative strategies based on the expression for the microcanonical rate in terms of the inverse Laplace transform of the thermal reaction rate. It is shown that simple application of the stationary-phase approximation (SPA) dramatically improves the performance of the microcanonical rates using RPMD, particularly in the low-energy region where tunneling dominates. Using the SPA as a Bayesian prior, numerically exact RPMD microcanonical rates are then obtained using maximum entropy inversion of the thermal reaction rates for both electronically adiabatic and non-adiabatic model systems. Finally, the direct-shooting method is revisited using the SPA-determined temperature for the internal ring-polymer modes, leading to a simple, direct-simulation method with improved accuracy in the tunneling regime. This work suggests a general strategy for the extraction of microcanonical dynamical quantities from RPMD (or other approximate thermal) simulations

AN ALTERNATIVE APPROACH TO DETERMINING THE ELASTICITY OF EXCESS DEMAND FACING THE UNITED STATES

The United States embarked on a policy assuming excess demands for commodities are elastic. Some analysts question the success of that policy and argue that excess demands for farm commodities are inelastic. The controversy is deepened because the two traditional techniques for determining excess demand elasticities yield opposing estimates. We use an alternative technique based on observed variation in commodity prices, production, and use. The point estimates show excess demands for wheat, coarse grains, soybeans, rice, and cotton are elastic. However, a one-sided bootstrap test cannot reject the null hypothesis that the excess demands for wheat, coarse grains, and soybeans are inelastic.Demand and Price Analysis,

State and Local Prevalence of Firearms Ownership: Measurement, Structure, and Trends

Of the readily computed proxies for the prevalence of gun ownership, one, the percentage of suicides committed with a gun, performs consistently better than the others in cross-section comparisons. It is readily computed for states and counties and has a high degree of validity when tested against survey-based estimates. It also appears valid as a proxy for changes over time in gun prevalence, at least at the regional level. Our analysis of this proxy measure for the period 1979-1997 demonstrates that the geographic structure of gun ownership has been highly stable. That structure is closely linked to rural tradition. There is, however, some tendency toward homogenization over this period, with high-prevalence states trending down and low-prevalence states trending up.

A corpus study of pseudogapping and its theoretical consequences

Piñon, Christopher (ed.)International audienceThis paper presents the results of a large-scale investigation of the use of NP-remnant pseudogapping (PG) in the COCA corpus. Discourseconditions on the use of noncomparative and comparative PG are discussed. It is shown that the data raise problems for mainstream gener ative analyses involving remnant-raising and an alternative interpretive analysis is suggested. The question of whether PG is a subcase of VPE is discussed