Vibration effects on setting pregnant women--subjects of various masses

An electrical simulation of a mechanical model of a 60 kg pregnant woman subjected to horizontal and vertical vibrations has been investigated by using a computer software package (MICRO-CAP II). The results have shown that mechanical vibrations affect the body segments differently based on their location, the kind of vibration and pregnancy development. The vibrations' effect on the body varies from segment to segment and a lady driver is affected by vibrations more than a lady passenger. Horizontal vibrations affect body segments (lower arm, upper arm, head, thorax, torso, cervical spine, and lumbar spine) more than vertical vibrations, while the thorax is affected by vertical vibrations, more than horizontal vibrations.     

Spatial climate variation pattern and regional prediction of rainfall in Jordan

Currently Jordan is facing various water problems accompanied by rapid population growth, urbanisation and industrialisation. It is of outmost importance to search for water resources augmentation possibilities leading to decision‐making procedures by addressing the rainfall sources as the main water resources in Jordan, through refined techniques. Point cumulative semivariogram (PCSV) samples are analysed in order to identify the regional dependence of the rainfall phenomena. Amman station is taken as a pivot site because of its location in the centre of the Kingdom, where the samples of the PCSV are calculated for eight systematic directions. Standard regional dependence function (SRDF) is obtained from the sample PCSV and the weighted average procedure is applied with the help of SRDF to predict the rainfall amounts. The radius of rainfall influence is determined for Amman in each direction. The cross‐validation methods are used to predict the rainfall in Amman using different samples representing along each direction. The result of cross‐validation method is acceptable in all samples with relative error not exceeding 10%, except in the desert sides where larger errors indicate weak regional dependence.     

Biaxial bending stresses and stress factors in trapezoidal and elliptical cross-sectional curved beams

Summary This paper deals with the general case of biaxial bending of a curved beam in space whose centerline is circularly curved. Stress equations at any point in the cross-section of the beam have been derived by using Winkler's method. Neutral planes were established and stress factors were found and tabulated for variable thicknesses, widths, and ratios of (R ₂/R ₁). Numerical examples for several cases are solved and are demonstrated in graphical manner.Nomenclature a semi-major axis of an ellipse - a ₁ distance from the centroidal point, along they axis to the interior fiber - a ₂ distance from the centroidal point, along they axis to the exterior fiber - A cross sectional area - A ₁ =a ₂+a ₁ - A ₃ =a ₂ ³+a ₁ ³ - A ₄ =a ₂ ⁴–a ₁ ⁴ - b semi-minor axis of an ellipse - b ₂ exterior fiber width - b ₁ interior fiber width - b =b ₂–b ₁ - F stress correction factor - h thickness of the beam - H - I _y moment of inertia abouty-axis - I _z moment of inertia aboutz-axis - I _yz product of inertia - J _y polar moment of inertia abouty-axis - J _z polar moment of inertia aboutz-axis - J _yz polar product of inertia - M _y bending moment abouty-axis - M _z bending moment aboutz-axis - R radius of curvature of the centroidal axis in the unloaded condition - R ₁ =R ₀–a ₁ - R ₂ =R ₀+a ₂ - x _z fiber width parallel toz-axis - y fiber distance from centroidal point, along they-axis - z distance of point from Ccentroidal point, along thez-axis - _E bending stress, elementary theory - _W bending stress, Winkler's theory With 21 Figures     

Assessing Groundwater Geospatial Variation Using Microgravity Investigation in the Arid Riyadh Metropolitan Area,Saudi Arabia: a Case Study

A combination of relative microgravity measurements at ground surface, and depth to water and water table measurements from adjacent wells were used to estimate geospatial variation of groundwater. A highly accurate portable Grav-Map gravimeter was used for gravimetric measurements at locations nearby a 42 well water table monitoring program. To efficiently correlate the two data sets, wells were clustered into five groups by geological unit and water saturation. Microgravity data was processed, interpreted, and correlated with both the depths to groundwater and the water table levels. Regression analyses revealed a strong negative correlation for microgravity and depth to groundwater in all five clusters; correlation coefficients varied between 0.70 and 0.97, and measured 0.78 over the entire study area. Microgravity values increased as groundwater depth decreased, likely because rising groundwater fills voids and fractures within soil and rocks, increasing rock density and therefore relative gravity. To validate the correlation, we superimposed a map of depths to water on the first derivative of microgravity measurements. The shallowest groundwater depths were positively related to the zero first derivatives, having intersection areas within a 75 % significance interval. Negative first derivatives covered the rest of the study area, with relative gravity decreasing with increasing groundwater depth. This technique can precisely and efficiently determine changes in subsurface geology and geospatial changes in depths to the groundwater table. Distances between microgravity stations should be small, to better detect small changes in gravity values, reflecting density contrasts underground.     

Preliminary Investigation of Copper Joints Soldered with Sn58Bi

In recent years, intensive studies have been carried out to find an alternative for Tin (Sn)-Lead (Pb) solder alloys with increasing demand over lower temperature solder alloys in current electronic packaging industry. High temperature operational solder alloys seem to produce drawback to other components on the printed circuit board (PCB). Low melting temperature Sn58Bi substrate as a potential replacement was investigated in this paper based on the melting properties, wettability, and shear strength. The Sn58Bi was soldered at a temperature below 200 ℃ on the Cu substrate, and the shear strength and contact angle were calculated. A peak temperature (melting temperature, TM) of 144.83 ℃ was identified. Single lap joint method was performed at a strain rate of 0.1 mm/min and an average shear strength of 23.4 MPa was found from three samples. The contact angle (wettability) was calculated to study the solder joint behaviour at reflow temperature of 170 ℃. The contact angle of the Sn58Bi was found to be 32.4 ° and considered to be desired value since the angle is less than 50 °. The low temperature soldering provides a preliminary result to allow further application on the real PCB.     

The effect of bacterial environmental and metabolic stresses on a laser-induced breakdown spectroscopy (LIBS) based identification of Escherichia coli and Streptococcus viridans

In this paper we investigate the effect that adverse environmental and metabolic stresses have on the laser-induced breakdown spectroscopy (LIBS) identification of bacterial specimens. Single-pulse LIBS spectra were acquired from a non-pathogenic strain of Escherichia coli cultured in two different nutrient media: a trypticase soy agar and a MacConkey agar with a 0.01% concentration of deoxycholate. A chemometric discriminant function analysis showed that the LIBS spectra acquired from bacteria grown in these two media were indistinguishable and easily discriminated from spectra acquired from two other non-pathogenic E. coli strains. LIBS spectra were obtained from specimens of a nonpathogenic E. coli strain and an avirulent derivative of the pathogen Streptococcus viridans in three different metabolic situations: live bacteria reproducing in the log-phase, bacteria inactivated on an abiotic surface by exposure to bactericidal ultraviolet irradiation, and bacteria killed via autoclaving. All bacteria were correctly identified regardless of their metabolic state. This successful identification suggests the possibility of testing specimens that have been rendered safe for handling prior to LIBS identification. This would greatly enhance personnel safety and lower the cost of a LIBS-based diagnostic test. LIBS spectra were obtained from pathogenic and non-pathogenic bacteria that were deprived of nutrition for a period of time ranging from one day to nine days by deposition on an abiotic surface at room temperature. All specimens were successfully classified by species regardless of the duration of nutrient deprivation.     

Pathogen identification with laser-induced breakdown spectroscopy: the effect of bacterial and biofluid specimen contamination

In this paper, the potential use of laser-induced breakdown spectroscopy (LIBS) for the rapid discrimination and identification of bacterial pathogens in realistic clinical specimens is investigated. Specifically, the common problem of sample contamination was studied by creating mixed samples to investigate the effect that the presence of a second contaminant bacterium in the specimen had on the LIBS-based identification of the primary pathogen. Two closely related bacterial specimens, Escherichia coli strain ATCC 25922 and Enterobacter cloacae strain ATCC 13047, were mixed together in mixing fractions of 10:1, 100:1, and 1000:1. LIBS spectra from the three mixtures were reliably classified as the correct E. coli strain with 98.5% accuracy when all the mixtures were withheld from the training model and classified against spectra from pure specimens. To simulate a rapid test for the presence of urinary tract infection pathogens, LIBS spectra were obtained from specimens of Staphylococcus epidermidis obtained from distilled water and sterile urine. LIBS spectra from the urine-harvested bacteria were classified as S. epidermidis with 100% accuracy when classified using a model containing only spectra from other Staphylococci species and with 88.5% accuracy when a model containing five genera of bacteria was utilized. Bacterial specimens comprising five different genera and 13 classifiable taxonomic groups of species and strains were compiled in a library that was tested using external validation techniques. The importance of utilizing external validation techniques where the library is tested with data withheld from all previous testing and training of the model was revealed by comparing the results against "leave-one-out" cross-validation results. Last, the effect of using sequential models for the classification of a single unknown spectrum was investigated by comparing the misclassification of two closely related bacteria, E. coli and E. cloacae, when the classification was first performed using the five-genus bacterial library and then with a smaller model consisting only of E. coli and E. cloacae specimens. This result shows the utility of using successively more targeted analyses and models that use preliminary classifications from more general models as input.     

Simultaneous energy harvesting and information processing in wireless multiple relays with multiple antennas

Wireless networks suffer from battery discharging specially in cooperative communications when multiple relays have an important role but they are energy constrained. To overcome this problem, energy harvesting from radio frequency signals is applied to charge the node battery. These intermediate nodes have the ability to harvest energy from the source signal and use the energy harvested to transmit information to the destination. In fact, the node tries to harvest energy and then transmit the data to destination. Division of energy harvesting and data transmission can be done in two algorithms: time-switching-based relaying protocol and power-splitting-based relaying protocol. These two algorithms also can be applied in delay-limited and delay-tolerant transmission systems. The previous works have assumed a single relay for energy harvesting, but in this article, the proposed method is concentrated on improving the outage probability and throughput by using multiple antennas in each relay node instead of using single antenna. According to our simulation results, when using multi-antenna relays, ability of energy harvesting is increased and thus system performance will be improved to great extent. Maximum ratio combining scheme has been used when the destination chooses the best signal of relays and antennas satisfying the required signal-to-noise ratio.