Large families of quaternary sequences with low correlation

A family of quaternary (Z₄-alphabet) sequences of length L=2^r-1, size M⩾L²+3L+2, and maximum nontrivial correlation parameter C_max⩽2√(L+1)+1 is presented. The sequence family always contains the four-phase family 𝒜. When r is odd, it includes the family of binary Gold sequences. The sequence family is easily generated using two shift registers, one binary, the other quaternary. The distribution of correlation values is provided. The construction can be extended to produce a chain of sequence families, with each family in the chain containing the preceding family. This gives the design flexibility with respect to the number of intermittent users that can be supported, in a code-division multiple-access cellular radio system. When r is odd, the sequence families in the chain correspond to shortened Z₄-linear versions of the Delsarte-Goethals codes     

Variations in total amino acid content of peanut meal

The amino acid levels of oil-free peanut meal prepared from 16 varieties of peanuts that had 24–30% protein content of the kernels were examined. Nearly two-fold variations in the limiting essential amino acids (lysine, isoleucine, methionine, threonine, and valine) were found and are reported. Data for the remaining amino acids also are included. Utilization of these variations in amino acid composition should assist the development of peanut protein of improved quality. An analytical procedure to measure amino acid composition of peanut meal with a high precision on duplicate samples and which requires 15 hr for hydrolysis for best accuracy is described. Presented at the AOCS Meeting, New Orleans, May 1973. Journal article 2634 of the Oklahoma Agricultural Experiment Station.     

Eastern and Western European policy on electricity infrastructure,interconnections and electricity exchanges

This paper focuses on the present and future state of the electric power sector, future development of European power systems interconnections and power exchanges, cooperation, and direction of reforming the industry. It discusses the deregulation process and experience in Scandinavia, electricity infrastructure in Hungary, challenges to the German electricity system as part of the western European interconnected system of the Union for the Coordination of Protection and Transmission of Energy (UCPTE), extension of European interconnections to the Black Sea and central African countries, together with the development of a Trans-European synchronized power system as seen from the East. It also examines the current situation and policy of Russia, Ukraine, Belarus, and Moldova taking into account the recently created new independent states (NIS)     

Tertiarybutylarsine for Metalorganic Chemical Vapor Deposition Growth of High Purity, High Uniformity Films

We have performed an extensive study of GaAs, Al_0.22Ga_0.78As, and In_0.16Ga_0.84As grown using tertiarybutylarsine (TBA) in an ultra-high purity metalorganic chemical vapor deposition multi-wafer reactor. Key results include: high purity TBA AlGaAs layers with the lowest p-type carrier concentrations (4 × 10¹⁴ cm⁻³) reported to date; 4K photoluminescence bound exciton linewidths as narrow as 4.3 meV; C, O. Si, and S concentrations below the secondary ion mass spectrometry detection limit; and InGaAs/GaAs quantum wells with 20K PL linewidths as narrow as 3.5 meV. We also observe a strong dependence of growth rates and doping efficiency on group-V partial pressure, possibly due to a competition between excess group-V species and group-Ill or Si species for group-Ill surface sites. Finally, we demonstrate record uniformity using TBA with an AlGaAs thickness variation of only ±1.4% across a 4 inch wafer.     

High-performance 1.06-/spl mu/m selectively oxidized vertical-cavity surface-emitting lasers with InGaAs-GaAsP strain-compensated quantum wells

We present the first room-temperature continuous-wave operation of high-performance 1.06-/spl mu/m selectively oxidized vertical-cavity surface-emitting lasers (VCSEL's). The lasers contain strain-compensated InGaAs-GaAsP quantum wells (QW's) in the active region grown by metalorganic vapor phase epitaxy. The threshold current is 190 /spl mu/A for a 2.5/spl times/2.5 /spl mu/m/sup 2/ device, and the threshold voltage is as low as 1.255 V for a 6/spl times/6 /spl mu/m/sup 2/ device. Lasing at a wavelength as long as 1.1 /spl mu/m was also achieved. We discuss the wavelength limit for lasers using the strain-compensated QW's on GaAs substrates.     

Variability in fatty acid composition amongArachis genotypes: A potential source of product improvement

Research on peanut (Arachis hypogeae L.) genotypes has shown a high degree of genetic variability in fatty acid composition. The two major oil fatty acids, oleic and linoleic, range between 36–69% and 14–40%, respectively, and together make up 75–85% of total fatty acids. The very long chain (C₂₀–C₂₄) fatty acids make up 4–9%, palmitic acid 7–13%, and stearic acid 2–5% of total fatty acids. Stability of oil samples as measured by length of autoxidation induction period at 60 C shows variable but statistically significant (P<0.01) correlations with levels of linoleic acid; peanut butter samples show similar patterns of stability. Selection for lower levels of linoleic acid in the development of new varieties of peanuts should results in products with significantly improved shelf life. Some genotypes show consistent differences in oil stability patterns that are not related to oil linoleic acid content. Analysis of entries from 16 wildArachis species collections revealed levels of oil linoleic acid higher than those found inA. hypogaea. One species,A. villosulicarpa, contained 49% linoleic acid and 21% very long chain acids. The range in linoleic acid withinA. hypogaea and availability of suitable techniques for measuring selection progress give scope for product improvement through breeding.     

Tidal power

Reviews the physics of tidal power, considering the gravitational effects of the Moon and Sun; semidiurnal, diurnal, and mixed tides; and major periodic components that affect the tidal range. Shelving, funneling, reflection, and resonance phenomena that have a significant effect on tidal range are also discussed. Basic parameters that govern the design of tidal power schemes in terms of mean tidal range and surface area of the enclosed basin are identified. Because energy extracted is proportional to the square root of the tidal amplitude, sites with large tidal amplitudes are best suited for tidal power developments, whereas sites with low tidal amplitudes have sluicing that may be prohibitive. Potential tidal energy developments are mentioned. Existing tidal energy plants are discussed. Tidal barrage design and construction using caissons is examined, as are alternative operating modes, development trends and possibilities, generation cost at the barrage boundary, sensitivity to discount rates, general economics, and markets. Environmental effects, and institutional constraints to the development of tidal barrage schemes are also discussed     

Implanted-planar-buried-heterostructure, graded-index,separate-confinement-heterostructure laser in GaAs/AlGaAs

For the implanted planar buried-heterostructure, graded-index, separate-confinement-heterostructure (IPBH-GRINSCH) laser in (AlGa)As/GaAs, ion implantation is used to form p-n-p-n current blocking layers and to create a buried-heterostructure waveguide. This results in significantly reduced fabrication complexity of high-quality, index-guided laser diodes compared to regrowth techniques, and in contrast to diffusion-induced disordering, allows for the creation of self-aligned, buried, blocking junctions. Kink-free, CW operation of single-stripe IPBH-GRINSCH lasers along with single-lobed near-field and far-field optical emission patterns, consistent with index-guided operation, is demonstrated