:Basil (Ocimumbasilicum L.) is an herbaceous annual aromatic herb that belongs to the Lamiaceae family. This study aimed to analyze the essential oil content and physicochemical properties of basil varieties stored under different drying methods and dried on different drying days. The fresh leaf of basil varieties was collected from the Wondo Genet Agriculture research center experimental field and subjected to open sun and shade drying methods and four drying days (0,5, 10, and 15). The sample was subjected to oven and hydrodistillation methods on each four particular drying days. The obtained essential oils were analyzed for physical properties (specific gravity and refractive index) and chemical composition using GC-MSD. As shown in the result of all-cause drying methods and drying days significantly affect the essential oil content and physicochemical properties of Basil Variety. In the case of Variety, Basil 02 has a high essential oil content than Basil 05 in the chemical composition, and different chemical compositions exist in both. In the case of drying methods, the sample dried under the shade is higher than in the open sun in essential oil content and physicochemical properties. In the case of different drying days, as the drying days increase, the essential oil content is significantly affected. The essential oil content and physicochemical properties of essential oil decrease as drying days increase for both basil varieties. Drying affects the chemical composition of the two variables, which means, as in the cause of open sun drying, affects the chemical composition more than shade drying as the drying days increase, and the chemical composition decrease. Therefore, this study provides evidence that drying herbs on different drying days and under drying conditions affect the essential oil content and physicochemical properties of essential oil.

A hydrographic survey vessel shows three -dimensional movements (Roll, Pitch and Heave) misalignment with respect to the vessel reference unit (VRU) due to environmental effects, such as wind, current, other vessel wakes, etc. These motions if ignored, cause errors in measured depth and in the positioning of the sounding. Hence the need of a motion sensor and gyroscope. However, the alignment of the multi-beam sonar head to the motion sensor and gyro (Octant) is critical to the accuracy of the determined depths. It is not possible to install the sonar head in perfect alignment with the motion sensor and gyroscope to the accuracy required. The synchronization of the GPS time with the Motion sensor and gyro, the latency of the position, as reported by the GPS as well as the velocity of sound in water are important parameters to account for the misalignment of the motion senor and the multi beam sonar head; this is called the Patch Test. In view of this, a patch test was done to ascertain the mounting angles of EMB 2058 Multi-beam sonar with Octan V installed onboard a survey vessel (Bitam). The result of the Patch test gives a row, pitch and heading value of -1.242˚, -4.92˚, and -0.48˚respectively. The speed of sound in water as measured ranges from; 1531.47m/s to 1531.60m/s within a minimum cast depth of 0.49m and maximum cast depth of 16.00m. The statistical analysis gives and average error of 2.642cm/m2 which was within acceptable standard as define by the International Hydrographic Organization (IHO).

The deflection of the vertical is an important parameter that combines both physical (astronomic) and geometric (geodetic) quantities. It is critical in such areas as datum transformation, reduction of astronomic observation to the geodetic reference surface, geoid modelling and geophysical prospecting. Although the deflection of the vertical is a physical property of the gravitational field of the earth; which almost all terrestrial survey measurements, with the exception of spatial distances, made on the earth surface are with respect to the Earth’s gravity vector, because a spirit bubble is usually used to align survey instruments. It has been ignored in most geodetic computation and adjustment. This research work is therefore aimed at computing the component of the deflection of the vertical component for part of Rivers State using a geometric method. This method involves the integration of Global Positioning System (GPS) to obtain the geodetic coordinate of points, precisely levelling to obtain the orthometric height of this point located within the study area. By least square using MATLAB program, the estimated deflections of vertical component parameters for the test station SVG/GPS-002 were; -0.0473” and 0.0393” arc seconds for the north-south and east-west components respectively. The associated standard errors of the North-south and East-west components were ±0.0093” and ±0.0060” arc seconds, respectively. The deflection of the vertical was also computed independently from gravimetric models of the earth as: ξ = 0.0204” ±0.0008814”, η = -0.0345” ±0.0014”; ξ =0.0157” ±0.000755”, η = -0.0246” ±0.0012”; ξ = -0.0546±0.0006014, η = -0.0208±0.0006014 for EGM 2008, EGM 1996 and EGM 1984 respectively. The two-tailed hypothesis test reveals that the estimated deflection component is statistically correct at 95% confidence interval. It was observed that the effect of the deflection of the vertical is directly proportional to the distance of the geodetic baseline. Therefore, including the derived component of deflection of the vertical to the ellipsoidal model will yield high observational accuracy since an ellipsoidal model is not tenable due to its far observational error in the determination of high-quality job. It is important to include the determined deflection of the vertical component for Rivers State, Nigeria.