Soil To Plant Transfer Factors of Natural Radionuclides in Khat (Catha endulis) from Igembe South Subcounty, Kenya

This study evaluated the soil to plant transfer factors of khat (Catha endulis) to determine the absorption potential of natural radionuclides. Soil and leaves of Khat were sampled from Igembe south subcounty, Kenya and analyzed for concentrations of primordial radionuclides using a Thallium doped NaI gamma ray detector. Soil to plant transfer factors were calculated from activity concentrations and radiological safety of the ingested radionuclides was determined by annual effective dose (IAED), internal hazard index (Hin) and risk assessment parameter (RAP). Test results showed that the average soil to plant transfer factors for 232Th,238U and 40K were 0.0825, 0.143 and 1.575 respectively. The transfer factors of 40K were greater than 1 in more than 88% of the samples. The soil to plant transfer factors varies directly with energy of the gamma ray emitted and inversely with activity concentration of the radionuclides. The average IAED, Hin, and RAP were 1.136±0.390mSv/y, 0.210±0.070, 0.0568±0.021% respectively. Radiation hazard indices were within the safe limits and the fatality percentage was negligible. Therefore, there is no radiation risk associated with chewing of the sampled khat, and most of the radionuclides present in soil are not absorbed by Khat

An Influence of Recycled Concrete Aggregate and Treated Waste Water Containing 50% GGBS Content in Light weight Concrete Mixes

Extraction of natural aggregates is expensive and has a huge impact on the environment. The main issues in sand and gravel mining are the large areas that are affected, ground water level changes, illegal mining, unsuitability of desert and marine sand, and costs of transport. Metallurgical waste can be used as a substitute for natural aggregates, the waste is recycled and the use of natural aggregates is reduced. Environmental sources are diminishing every day and hence, usage of available sources become even more important..The novelty of this research reports the experimental examination of applying Recycled Aggregate (RA), Treated wastewater (TW) and GGBS in concrete. Four groups of mixes were developed (Groups NW, TW, NWG, and TWG) with each group consisting of four mixes, providing a total of 16 mixes. Group NW: 100% Natural Water (NW) with different percent ratio of RA contents Group TW: 100% Treated waste water (TW) with different percent ratio of RA contents Group NWG: 100% Natural Water (NW) and 50% GGBS (replacement with Portland cement [PC]) with different percent ratio of RA content Group TWG: 100% TW and 50% GGBS (replacement with PC) with different percent ratio of RA contents The test result are compressive strength tests after 1,7,15, and 28 days. The statistical analysis results showed that the effect on concrete compressive strength was only significant when 20% RA was used in concrete exposed to TWW with 50% replacement of GGBS

Preparation and Study of the Physical Properties of CdSe Films Deposited by a Chemical Bath Method and Exposed to Neutron Irradiation: Effect of neutron irradiation on a CdSe film prepared

This study deals with the preparation of CdSe films using two sources of cadmium, (CdCl2) and (CdSO4), and studying the effect of neutron irradiation on their optical and structural properties. Using CBD method, the films were prepared on glass substrates at a temperature of 50 •C, with a deposition time of 3 hours. These films were exposed to the neutron beam from the radioactive source (Am241-Be10) with a neutron flux (3*105 n/cm2.s) and an energy of 5 MeV for 7 days. It was noted that neutron irradiation has a significant effect on the physical properties of the films. Using a UV-V spectrophotometer, the optical properties of the films were studied. It was found that the absorption coefficient (?) and the energy gap increase with irradiation, and from the following XRD, FESEM and EDX measurements, the shape and structure of the prepared and irradiated films were determined. X-ray measurements have shown that there are preferred directions for grain growth [111], [220], and [311]. It was also observed that the grain size increases, while the relative density decreases with irradiation. As for FESEM measurement, it was noted that the surface shape of the films is greatly affected when exposed to neutron radiation

Approximated transverse deflection of sandwich beam with 2D-FG and ceramic face sheets and 1D-FG core

The approximated numerical deflection of a sandwich beam with two directional functionally graded (2D-FG) and ceramic face sheets and one directional functionally graded (1D-FG) core, namely SW2D1DC, is presented under uniform load and various boundary conditions. The finite element code written in Matlab is applied in this article to investigate the influences of material properties on transverse deflections. The results of this article are given and compared with other results in the references to verify the feasibility of the application. This study also provides some more information about the characteristics of SW2D1DC beams

An Optimized Sandwich Bumper Beam for Child Occupant Head Injury Prevention

Child fatalities from motor vehicle crashes are recently being considered as a global problem. Various mitigation systems have been proposed, but are still not optimum. Designing energy absorption vehicle front has been one of the methods used to minimize vehicle deceleration. This in addition to child restraint seat could help minimize child injuries especially to the most sensitive part of human body, the head. Sandwich bumper beam absorbs huge kinetic energy by plastic deformation and lead to reduction of vehicle deceleration and subsequent lower occupant injuries. In this work, optimization was carried out seeking for the optimum design of composite beam thickness ( and foam thickness (  of a sandwich bumper that will minimize Head Injury Criteria ( and ) to child occupant at 48 km/h frontal impact. Sampling design of the bumper and beam thickness applying design of experiment and finite element (FE) crash simulations using LS DYNA was applied to evaluate the three year old (3YO) child model head injury responses. Optimization models were developed which were in turn used in optimization process. The optimization was carried out using polynomial Response Surface Method (RSM) for  and . The bumper beam and foam thickness that gives a minimum   and  of 386.6 and 311.5 respectively are 100 mm  with 1 mm . Lastly, the work, suggested the need for employing the relationship that exist between child occupant response and bumper material and thickness in design considerations

Design and Implementation of a Three-Phase Asynchronous Motor Drive Based on a Single Chip Three-Phase Bridge Driver IR 2132

Technological developments in this world are growing quite rapidly, one of which is the development of the use of electric motors. There are many types of electric motors today, for example asynchronous electric motors or often called induction motors. In its use, asynchronous motors are widely used on an industrial scale. As time went by, asynchronous motor control itself also began to develop, starting from mechanically using switches to using inverters. The use of a three-phase IGBT inverter to control a three-phase asynchronous motor will be discussed in this research. The inverter control itself will use the SPWM topology, where the SPWM topology has advantages over the PWM topology. Apart from that, this research will use a single chip three-phase bridge driver IR2132 as the IGBT driver. This IC has advantages, one of which is that it has an internal deadtime, where deadtime is very necessary in controlling the three-phase inverter so that short circuits do not occur between the legs. This research shows that with a certain DC Link input voltage, it is possible to regulate a three-phase asynchronous motor using SPWM topology to control an IGBT inverter

Control of A Switched Reluctance Motor Based on Asymmetric Converter and Digital Signal Controller for Forward and Reverse Mode

The Switched Reluctance Motor (SRM) is one of the best choices for industrial and electric vehicle applications, selected for its optimal performance. This is due to the advantages of SRM, including the use of permanent magnet-free technology and a simple construction consisting of an iron core on the rotor and stator windings. A rotary encoder is utilized to detect the rotor position due to its high precision. However, synchronization with the rotor position is required during installation to achieve optimal SRM performance. The rotor position obtained from the rotary encoder is processed by the digital signal controller to determine the firing angle on the rotor. The research objective is to control the SRM to rotate in both directions. To support this study, laboratory tests were conducted for validation by changing the phase sequence in the asymmetric converter, causing differences in the three-phase current waveforms for forward and reverse rotations. The results of this research show that the SRM can rotate bidirectionally

Design and Development of a Low-Cost Multi-Channel Re-Programmable Electro-Pneumatic Actuator Kit

The objective of the research was to develop a low-cost, multi-channel electro-pneumatic actuator kit that would be conveniently accessible for students' learning experiences, trainings, and research at the individual and academic level. The essential feature of this kit was the inclusion of multi-channel outputs, which implies that the student may not only examine the behavior of basic pneumatic actuators but also train their minds to operate complicated actuation systems. With this electro-pneumatic actuation kit, a student can build and utilize it in a variety of research areas, as well as regulate a system synchronously or asynchronously with greater efficiency. The device is portable, inexpensive, and simple to use. It has a power source of 12 VDC for the electrical circuit and can provide a maximum pressure of 90 kPa as well as vacuum of -40 kPa. Relays were being integrated to satisfy the smooth automation of the kit. It features the MPX700 differential pressure sensor, which allows the user to measure and manage the needed pressure. All of the components were controlled by the Arduino Board, which is affordable and can be programmed to do the required function. With this research, academic institutions will be able to create their own kits for their students, allowing them to discover numerous new inventive concepts

Second Law Analysis in a Non-Newtonian Fluid Flow in an horizontal Channel with Narrowing and Widening

This work studies the flow of a non-Newtonian power-law fluid with viscous dissipation through a pipe with a variable expand ratio (B).The influence of the power law index (n), expand ratio (B), Darcy number (Da) and  Brinkman number(Br) on heat transfer and thermodynamics irreversibility is investigated. Equations of the problem are solved numerically using COMSOL software. Results show that heat transfer and entropy generation are deeply affected by selected governing parameters. Both thermal entropy generation and average Nusselt number are maximal at low power index and at high medium permeability. Power index effect is insignificant at relatively low Darcy number. Considering viscous dissipation with high Brinkman number, heat transfer direction can be reversed at moderate Darcy number and high power index

Dynamic Force Analysis on Blades of Centrifugal Pumps using Computational Fluids Dynamics Simulations

Mechanical stress on the blade of a centrifugal pump is a crucial factor in the design and operation of hydraulic pumps. Therefore, in this study, the tangential force on the blade of a centrifugal pump at different flow rates and directions was investigated using Computational Fluid Dynamics (CFD) simulations. The CFD simulations were performed based on the k-? turbulence model and were validated through experimental measurements. The study revealed that the tangential force is dependent on the flow rate of the fluid being pumped, and understanding how it changes with varying flow rates is essential for optimizing the performance of the pump and preventing potential fractures. On the other hand, the absolute pressure on the blade was also investigated. The absolute pressure distributions on the blade pressure side, suction side, leading edge, and trailing edge were analyzed for different flow rates. The highest pressure distribution is found on the pressure side than the suction side. On the blade pressure side, a relatively large pressure is found near the trailing edge. Overall, the study provides insights into the complex relationship between flow rate and tangential force in centrifugal pumps and highlights the importance of understanding this relationship for successful pump design and operation