Rainfall parameters from disdrometer dropsize measurements at a tropical station

The rain dropsize distributions measured by a disdrometer in 21 rain events consisting of 1, 640one-minute dropsize spectra have been analyzed for a tropical station, Ile-Ife (geog. lat. 7.5°N, long 4.5°E) in South-Western Nigeria. Empirical power law relations of the form Y = aR^b have been obtained between the rainfall rate R, the radar reflectivity factor Z, liquid water content M, optical extinction σ and the median volume diameter D₀ for three types of rainfall. A power law relationship was also obtained between the median volume diameter D₀ and the liquid water content M. The variability in a and b with rain parameters, rain events and rain types is discussed. The empirical relations have been compared with existing relations for other parts of the world, for their utilization in radar meteorology and radar engineering.     

Rain induced depolarization from 1 GHz to 300 GHz in a tropical environment

The rain induced depolarization in a tropical environment has been studied using a tropical raindrop size distribution developed by Ajayi and Olsen (A-O). The differential attenuation, differential phase shift and cross polarization discrimination, XPD, were computed over a frequency range of 1GHz to 300GHz for spheroidal drops and up to 33GHz for Pruppacher-Pitter drops. The variations of XPD with frequency, rainfall rate and copolar attenuation, CPA, were investigated. A mathematical relationship was established between the XPD and the CPA, canting angle and frequency of propagation from 5GHz to 300 GHz for spheroidal drops and up to 33 GHz for Pruppacher-Pitter drops. The results obtained using the A-O drop size distribution have been compared with those assuming the Laws and Parsons (L-P) distribution. The Pruppacher-Pitter drop shape has been found to give rise to higher XPD, especially at low CPA and high frequencies.     

OILFIELD BRINES OF METEORIC AND CONNATE ORIGIN IN THE EASTERN NIGER DELTA

A study of oilfield brines in the Afam, Imo River, Bodo-West and Umuechem oilfields in the Eastern Niger Delta petroleum sub-province of Nigeria was undertaken in an attempt to determine their genetic affinities.
On the basis of their contents of bicarbonate, chloride and sulphate ions, and total dissolved solids, most of the formation waters from the Imo River oilfield are shown to be meteoric in origin, whereas those from Afam, Bodo-West and Umuechem are connate waters. The relationship betwen salinity and total dissolved solids can be expressed by a simple linear equation.
Formation-water resistivity and total dissolved solids from these oilfields are parabolically related. The amount of total dissolved solids is also depth-controlled, and increases with depth. This relationship is thought to be a function of post-depositional processes.     

Prediction of structural response to blast –induced vibration in Kopek Construction Quarry,Ikere – Ekiti,Ekiti State,Nigeria

The responses of adjoining structures to blast induced ground vibrations emanating from Kopek Construction Quarry, Ikere – Ekiti in Ekiti State were evaluated and predicted. Five off site receptors at predetermined distances from the blast source were chosen and the Peak Particle Velocity (PPV) at each receptor during blasting was estimated using the squared root scaled distance equation. The estimated PPVs were compared with the USBM – RI 8705 reference. The results showed that the blast induced vibrations from the quarry site were within the recommended limits and were insignificant to warrant concerns of causing structural damages to buildings in proximity to the quarry site with the given blast design parameters.     

Secure data processing for IoT middleware systems

The Journal of Supercomputing - Increasingly, more manufacturing companies are equipping their products with smart capabilities which allow them to provide more informed services to customers....     

Synthesis and structure-activity relationship of the isoindolinyl benzisoxazolpiperidines as potent,selective, and orally active human dopamine D4 receptor antagonists

A new class of potent dopamine D(4) antagonists was discovered with selectivity over dopamine D(2) and the alpha-1 adrenoceptor. The lead compound was discovered by screening our compound collection. The structure-activity relationships of substituted isoindoline rings and the chirality about the hydroxymethyl side chain were explored. The isoindoline analogues showed modest differences in potency and selectivity. The S enantiomer proved to be the more potent enantiomer at the D(4) receptor. Several analogues with greater than 100-fold selectivity for D(4) over D(2) and the alpha-1 adrenoreceptor were discovered. Several selective analogues were active in vivo upon oral or intraperitoneal administration. A chiral synthesis starting from either D- or L-O-benzylserine is also described.     

The Effects of Specimen Geometry on the Plastic Deformation of AA 2219-T8 Aluminum Alloy Under Dynamic Impact Loading

The effects of specimen geometry on shear strain localization in AA 2219-T8 aluminum alloy under dynamic impact loading were investigated. The alloy was machined into cylindrical, cuboidal and conical (frustum) test specimens. Both deformed and transformed adiabatic shear bands developed in the alloy during the impact loading. The critical strain rate for formation of the deformed band was determined to be 2500 s^?1 irrespective of the specimen geometry. The critical strain rate required for formation of transformed band is higher than 3000 s^?1 depending on the specimen geometry. The critical strain rate for formation of transformed bands is lowest (3000 s^?1) in the Ø5 mm × 5 mm cylindrical specimens and highest (> 6000 s^?1) in the conical specimens. The cylindrical specimens showed the greatest tendency to form transformed bands, whereas the conical specimen showed the least tendency. The shape of the shear bands on the impacted plane was also observed to be dependent on the specimen geometry. Whereas the shear bands on the compression plane of the conical specimens formed elongated cycles, two elliptical shaped shear bands facing each other were observed on the cylindrical specimens. Two parallel shear bands were observed on the compression planes of the cuboidal specimens. The dynamic stress–strain curves vary slightly with the specimen geometry. The cuboidal specimens exhibit higher tendency for strain hardening and higher maximum flow stress than the other specimens. The microstructure evolution leading to the formation of transformed bands is also discussed in this paper.     

Functional and tableting properties of acetylated and oxidised finger millet (Eleusine coracana) starch

The functional and tableting properties of native (NaFM) and chemically modified (by acetylation, AcFM; and oxidation, OxFM) finger millet starches were investigated. The tablet formation properties of the starches were assessed by Heckel and Kawakita analysis. The swelling power and solubility of the starch increased with increase in temperature with AcFM having the highest swelling power, while OxFM had the highest solubility. X‐ray diffractometry showed that the starches had the characteristic ‘A’ pattern with strong peaks at 3.78, 4.37, 4.87, and 5.17 Å. Chemical modification causes rupture of some starch granules as revealed by the Scanning Electron Micrograph. Chemical modification also leads to improved gelatinisation profile, with reduction in ΔH_gel from 9.64 J/g (NaFM) to 3.88 J/g (AcFM) and 8.76 J/g (OxFM). The bulk density and Hausner's ratio increased after chemical modification of the starch. Chemical modification reduced the mean yield pressure, P_y (Heckel analysis) but increased the deformability P_k (Kawakita analysis) of the starch compacts. Chemical modification also increased the crushing and tensile strength of the starch compacts, but lowered its disintegration time and friability.