The Quality Control of Engineering Properties for Stabilizing Silty Nile Delta Clay Soil,Egypt

Clay soil with low-bearing capacities can present great problems underlying pavement and light structures due to uncertainty associated with their performance. This paper describes a sonic based testing methodology for quality control of a surface stabilized soil. From an engineering aspect, an increase in water content has a number of disadvantageous consequences: cohesion decreases, the soil swells, the alternating dry-out/shrinkage and wetting/swelling effects destroy the rock or a soil structure. Cement is mixed into the soil to increase both the strength and the usability of local soils in constructions purposes. This is to overcome the problems by strengthening the soil underlying the structure or diminishing the leads transmitted from the foundation to the soil. The compressive strength of the stabilized soil is highly dependent on the type of soil, moisture content, cement content, and compaction work, and can therefore vary significantly in the field. The authors performed the quality control by measuring the sonic and tensile strength velocity in the stabilized soil that has been correlated to compressive strength in native materials. The improvement of the soil materials by the addition of cement could make the material suitable as filling materials, foundation and/or a road base construction. The quality control for the stabilized soils was investigated using sonic measurements and strength gain. The test methods were performed to evaluate the degree of improvement achieved through the measurement of compression and shear-wave velocities of the soil under study. Scanning electron microscopy and electron dispersive X-ray analyses were performed on raw and laboratory treated for qualitative understanding the strength minerals formed during stabilization. The sonic test showed a considerable improvement with curing time and percentages of stabilizer. Mineralogical studies indicated the formation of silica and alumina hydrates along with interwoven structure of cement treated clay particles suggesting adequate mixing of the soil and binder owing to the strength of the soil materials.     

Review: Satellite-based remote sensing and geographic information systems and their application in the assessment of groundwater potential, with particular reference to India

Various hydrological, geological and geomorphological factors play a major role in the occurrence and movement of groundwater in different terrains. With advances in space technology and the advent of powerful personal computers, techniques for the assessment of groundwater potential have evolved, of which remote sensing (RS) and geographic information systems (GIS) are of great significance. The application of these methods is comprehensively reviewed with respect to the exploration and assessment of groundwater potential in consolidated and unconsolidated formations in semi-arid regions, and specifically in India. The process of such assessment includes the collection of remotely sensed data from suitable sensors and the selection of thematic maps on rainfall, geology, lithology, geomorphology, soil, land use/land cover, drainage patterns, slope and lineaments. The data are handled according to their significance with the assignment of appropriate weights and integrated into a sophisticated GIS environment. The requisite remote sensing and GIS data, in conjunction with necessary field investigations, help to identify the groundwater potential zones effectively.     

A Baseline Assessment of Coral Reef in Malacca Straits,Malaysia

Coral reefs along the Malacca Straits (MS) are poorly developed mainly due to turbidity and sedimentation. This study describes the health status and community structure of the corals in Cape Rachado, West Coast of Peninsular Malaysia (WCPM), utilizing the Coral Video Transect (CVT) technique. All the survey transects were categorized as ‘fair’ coral conditions (27.39 ± 5.41%–48.56 ± 18.96%) with the reef floor mainly covered by corals and sediment. Twelve families of coral comprised of 25 distinct genera were identified. Coral communities were differentiated into four clusters with each being predominated by Galaxea, Diploastrea, Fungia and Pectinia respectively. Among all, Pectinia is the most spectacular genera and dominated the survey area. Along the MS, Favia, Favites and Porites are commonly found while Porites and Pectinia dominated the reefs. Low coral cover and diversity was recorded in MS as compared to the reefs in the South China Sea (SCS). The most prominent results include changes in the dominant coral from Porites to Pectinia while some species such as Acropora were absent from the study area. Based on the presented data, the reef in the study area was predominantly occupied by sediment and the coral communities were formed by a species with a high tolerance to turbidity and sedimentation.     

Influence of geomagnetic field on the motion of low satellites

The first aim of the present work is to compute a more accurate and recent model for the Earth’s magnetic field. The second aim is to determine the effects of the Earth’s magnetic field on the motion of a charged artificial satellite to evaluate the variations of the orbital elements of the satellite due to these effects. The magnetic field and its variation with time have been studied at different heights, longitudes and latitudes. The geomagnetic field is considered as a multiple potential field and the electrical charge of the satellite is assumed to be constant. A new computer code has been constructed to follow the components of the magnetic field in spherical harmonic models. The Gauss equations are solved numerically. The results concentrate on the computation of the numerical values of orbital perturbation for the case of a low Earth satellite. RS-1 satellite and space craft gravity probe B (GPB) are chosen as cases of studies for a detailed numerical analysis.     

Scaling and self‐similarity in one‐dimensional unsteady open channel flow

The conditions under which the Saint Venant equations system for unsteady open channel flow, as an initial–boundary value problem, becomes self‐similar are investigated by utilizing one‐parameter Lie group of point scaling transformations. One of the advantages of this methodology is that the self‐similarity conditions due to the initial and boundary conditions can also be investigated thoroughly in addition to the conditions due to the governing equation. The obtained self‐similarity conditions are compared with the scaling relationships that are derived through the Froude similitude. It is shown that the initial–boundary value problem of a one‐dimensional unsteady open channel flow process in a prototype domain can be self‐similar with that of several different scaled domains. However, the values of all the flow variables (at specified time and space) under different scaled domains can be upscaled to the same values in the prototype domain (at the corresponding time and space), as shown in this study. Distortion in scales of different space dimensions has been implemented extensively in physical hydraulic modelling, mainly because of cost, space and time limitations. Unlike the traditional approach, the distinction is made between the longitudinal–horizontal and transverse–horizontal length scales in this study. The scaled domain obtained by the proposed approach, when scaling ratios of channel width and water depth are equal, is particularly important for the similarity of flow characteristics in a cross‐section because the width‐to‐depth ratio and the inclination angles of the banks are conserved in a cross‐section. It is also shown that the scaling ratio of the roughness coefficient under distorted channel conditions depends on that of hydraulic radius and longitudinal length. The proposed scaling relations obtained by the Lie group scaling approach may provide additional spatial, temporal and economical flexibility in setting up physical hydraulic models. Copyright © 2013 John Wiley & Sons, Ltd.     

Automatic detection of near surface geological and hydrological features and investigating their influence on groundwater accumulation and salinity in southwest Egypt using remote sensing and GIS

This study employs two automated algorithms, the topographic fabric and the deterministic eight-node (D8), to reveal near surface geological fractures and their associated paleodrainages network from a 90?m DEM of the Shuttle Topographic Radar Mission sensor. The topographic fabric algorithm, which calculates the slope and aspect which define a vector normal to the earth’s surface and then compute direction cosines of normal vector at each point, was used to auto-detect fault zones. The deterministic eight-node (D8) algorithm, which determines in which neighbouring pixel any water in a central pixel will flow naturally, was used to delineate paleodrainages concealed beneath sand sheets. Seven sets of geological structures were recognized. Their major trends were found to be in the S46°W, S58°W, S81°W, N107°W, N–S, E–W and N152°W and share similar trends of the revealed paleodrainages. The results suggest a strong spatial relationship between the features extracted from DEM and groundwater potential.     

Automatic Feature Extraction Module for Change Detection in Al Ain,UAE: Analysis by Means of Multi-temporal Remote Sensing Data

Monitoring new changes in cities adjacent to dynamic sand dunes requires precise classifier technique. Unlike traditional techniques of supervised classification which use training sites, the integration of image transformation tasseled cap and automatic feature extraction module based on spectral signatures has provided to be sensitive and realistic techniques with time and cost effective. The proposed module was applied to Al Ain district, United Arab Emirates (UAE). The module consists of four steps in terms of segmentation, thresholding and clustering and computing attributes. The obtained greenness and classified maps were then enhanced by applying a 3?×?3 Sobel filter. The new changes were detected by combining the multi-temporal greenness and classification maps. Accuracy assessment and quantitative analysis were performed using confusion matrix and ground truthing. The results showed significant increasing in urban and agricultural areas from the year from 1990 to 2000 compared with the period of time from the year 2000 to 2006. The image difference showed that the vegetation and building classes had increased 7.58 and 20.28 km² respectively. This study showed that image difference and fuzzy logic approach are the most sensitive techniques for detecting new changes in areas adjacent to dynamic sand dunes.     

Examining the utility of random forest and AISA Eagle hyperspectral image data to predict Pinus patula age in KwaZulu-Natal,South Africa

High-data dimensionality is a common problem in hyperspectral data processing. Consequently, remote sensing techniques that reduce the number of bands are considered essential tools for most hyperspectral applications. The aim of this study was to examine the utility of the random forest ensemble to select the optimal subset of hyperspectral bands to predict the age of Pinus patula stands. Airborne AISA Eagle hyperspectral image data were collected over the study area. The random forest ensemble was used to test whether the forward or backward variable selection methods could identify the optimal subset of bands. Results indicate that both the selection methods produced high-predictive accuracies (root mean square error = 3.097 years). However, the backward variable selection method utilized 206 bands for the final model, while the forward variable selection utilized only a small subset of non-redundant bands (n = 9) while preserving the highest model accuracy (R ² = 0.6).     

Coupling of remote sensing data and environmental-related parameters for dengue transmission risk assessment in Subang Jaya,Malaysia

In Malaysia, the endemic level of dengue fever (DF) has already changed morbidity indicators, and the magnitude of these incidences in the last few years has surpassed the incidences of all other diseases of compulsory notification. The reasons for the dramatic emergence of DF are complex and not well understood. There are many factors that contribute to the epidemiological conditions that favour viral transmission by the main mosquito vector. This study, therefore, is filling this gap by analysing the impact of dengue incidence at a local (Subang Jaya) scale using environmental factors. Meteorological data and land-use pattern were consolidated using geographic information system (GIS) and its components as an analytical tool. We have shown that weather variables (relative humidity, temperature and precipitation) have significant correlation with DF incidence with seasonal variation. Besides land-use pattern, DF incidence shows the higher distribution in the residential area, followed by commercial and industrial area. This is due to the higher population density in residential area as well as favourable places for the breeding of dengue-carrying Aedes mosquitos created by humans in the residential area, especially one-storey houses. The analysis on the trends of DF incidence towards various housing types indicate that most of the victims’ houses fall into interconnection houses and mixed houses types compared to the independent houses area. The outcome driven from this analysis suggested that each character of the environmental factors has their own risk towards dengue incidence. In line with that, it is possible to develop a dynamic model of DF transmission using the knowledge produced by this comprehensive time series data and the results provided by the different analyses.     

Turbidity Removal from Wastewaters of Natural Stone Processing by Coagulation/Flocculation Methods

The effectiveness of coagulation (at pH values of 6, 7.5, and 9), flocculation (at pH 9), and coagulation plus flocculation (at pH 9) on turbidity removal from natural stone (travertine) processing wastewaters (NSPW) were examined by applying classical sedimentation tests. FeCl₃·6 H₂O, AlCl₃, and Al₂(SO₄)₃·16 H₂O were used as coagulants and a polyacrylamide based anionic polymer was used as the flocculant. In this way, it was found that the coagulation method alone was not sufficient to purify NSPW, whereas flocculation and coagulation plus flocculation methods provided superior purification. Among the coagulants used, AlCl₃ gave the best result in terms of turbidity removal by coagulation from NSPW at pH 6 and 9, whereas the turbidity removal performances of the three coagulants were almost identical at pH 7.5. In addition, relatively low pH (i. e., pH 6) improved the purification performance of all coagulants. During coagulation of NSPW at pH 6, a charge neutralization mechanism played a decisive role in turbidity removal. However, in neutral (pH 7.5) and slightly basic (pH 9) media, a sweep coagulation mechanism was predominant. For flocculation of NSPW, the basic mechanism comprised of polymer bridging.