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Millimeter-wave (mmWave) networks with the frequency spectrum ranging from 30 GHz (with wavelength 10 mm) to 300 GHz (with wavelength 1 mm), can support massive wireless data in fifth-generation (5G) systems. Importantly, large colocated antenna elements can be exploited at the base station (BS) to facilitate beam-steering synthesis along the users' directions. This paper proposes the Butler matrix (BM) frequency diverse retrodirective array (BM-FDRA) beamforming network at the BS for multiuser communications in mmWave networks. We utilize the orthogonal feature of the M × M BM with M elements of the FDRA to create directional beams for concurrent transmission towards different users in range-angle locations. The proposed scheme has the following merits: (a) there is beam-steering orthogonality without beam interferences and (b) there is automatic tracking functionality, i.e., the prior knowledge on the user location is not required by the proposed BM-FDRA at the BS. The proposed method can serve multiple users concurrently using the beam-steering orthogonality property. Furthermore, performance metrics such as the multiaccess secrecy sum rate (SSR) model, bit error rate (BER), system capacity, and energy efficiency are examined. The proposed BM-FDRA scheme achievements are highlighted via simulation results. [ABSTRACT FROM AUTHOR]

ABSTRACT Response surface methodology was used to study the effect of extruder characteristics on product quality of rice-groundnut-cowpea extrudates using a single-screw extruder. The combined effect of cowpea (0-20%), groundnut (0-10%) and feed moisture (12.02-44.06%) were used to formulate the products. Product moisture, protein, fat, ash, bulk density, expansion ratio, water absorption capacity (WAC) and swelling capacity were determined. Well-expanded rice-legume blend extrudates of less bulk density and lower moisture content were produced at low feed moisture. Addition of legumes resulted in significant increases in protein, fat and ash contents of the rice-legume extrudates while increasing cowpea increased all the physico-functional properties. The models developed gave R2 values ranging from 64.01% (WAC at 70C) to 86.5% (bulk density) and suggested that the optimal process variables of low feed moisture (10-12%), cowpea level (20%) and groundnut level (10%) would produce ready-to-eat puffed snack with enhanced nutritive value and physico-functional properties from rice-groundnut-cowpea blend extrudates. PRACTICAL APPLICATIONS Rice constitutes a primary food for millions of people in sub-Saharan Africa, Asia and Latin America, where it forms a major source of proteins and calories in the diet of large segments of the population. However, its protein is 'incomplete' and is deficient in the essential amino acids such as lysine and methionine. Fortification with legumes (groundnut and cowpea) has shown to lead to improvement in the total protein quality and quantity. Extrusion cooking involves a high-temperature short-time process, whereby a single- or mixed-food material is modified through the unique combination of high temperature, pressure and shear forces causing large numbers of complex changes to the food. Extrusion cooking of the rice-groundnut-cowpea blends is expected to produce a convenient puffed snack food, ready-to-eat and breakfast cereal of high nutritional value, comprising of complementary proteins that have increased nutritional value and better product of physical and functional characteristics. [ABSTRACT FROM AUTHOR]