Teaching ultrasonics using spreadsheets

Whenever an ultrasonic wave encounters a boundary between two media it is partially reflected and refracted, as any acoustic wave would be. Unlike light, the wave also undergoes mode conversion so that in the general case a single incident wave could produce two reflected waves and two refracted waves. The angles which define the path of the wave are determined by Snell’s law and are easily calculated. The relative amplitudes, on the other hand, require quite complicated formula when the angle of incidence is anything other than 0 degrees. This problem gets compounded when the angle of the incident wave goes beyond the first critical angle. At this point the angle of the refracted wave becomes imaginary and the equations to calculate the relative amplitudes become complex. This paper describes a tool that has been developed, using a spreadsheet, which performs the calculations for all incident angles. The user selects the media and the type of incident wave and the resulting waves are shown graphically as well as numerically. The tool was developed primarily as part of an undergraduate course on ultrasonic testing, but could be used more widely

Sub 1GHz M2M communications standardization: The advancement in white space utilization for enhancing the energy efficiency

Energy efficiency of machine to machine (M2M) communications terminals is one of the major design goals of M2M networks, resulting from anticipated over 50 billion M2M communications devices to be deployed into the networks by 2020 [1]. The stakeholders in the M2M communications have observed that it will be environmental and economic catastrophic to deploy M2M communications devices without solving the energy inefficiencies associated with wireless devices that are expected to be used for M2M communications. In view of the aforementioned energy challenge, sub 1GHz spectra have provided enormous opportunities that can be energy efficient, cost effective and coverage efficiency which can be utilized for M2M communications. This work will evaluate the energy efficiency benefits of optimized Sub 1GHz spectra for M2M communications

A new channel selection algorithm for the Weightless-N Frequency Hopping with lower collision probability

There are different techniques used by Machine-to-machine (M2M) communications technologies to mitigate collision problem and data loss. One of these techniques is Frequency Hopping (FH), which is used by Weightless-N technology with a special random channel selection algorithm. In such a system, the probability of a message collision mainly depends on the randomisation algorithm used to access channels. This paper provides a novel randomisation algorithm for the channel selection process of the Weightless-N system. The new proposed algorithm is based on a uniform randomisation distribution and called a Uniform Randomisation Channel Selection Technique (URCST). This new algorithm provides a better system performance and lower probability of collision. In addition, it is faster and easier than the Mersenne Twister algorithm

Modelling, simulation and experimental validation of nonlinear dynamic interactions in an aramid rope system

Vibration phenomena taking place in lifting and hoist installations may influence the dynamic performance of their components. For example, in an elevator system they may affect ride quality of a lift car. Lateral and longitudinal vibrations of suspension ropes and compensating cables may result in an adverse dynamic behaviour of the entire installation. Thus, there is a need to develop reliable mathematical and computer simulation models to predict the dynamic behaviour of suspension rope and compensating cable systems. The aim of this paper is to develop a model of an aramid suspension rope system in order to predict nonlinear modal interactions taking place in the installation. A laboratory model comprising an aramid suspension rope, a sheave/pulley assembly and a rigid suspended mass has been studied. Experimental tests have been conducted to identify modal nonlinear couplings in the system. The dynamic behaviour of the model has been described by a set of nonlinear partial differential equations. The equations have been solved numerically. The numerical results have been validated by experimental tests. It has been shown that the nonlinear couplings may lead to adverse modal interactions in the system

Scheduling process for the M2M communications system in smart cites

The development of Machine-to-Machine communications systems has been increasing recently, especially considering that they have a wide range of applications in smart cities and the Internet of Things (IoT). However, with the massive number of connected devices in such applications, the problem of message collision becomes a vital factor that significantly affects the reliability of the M2M systems. The research project employs the Weightless-N type M2M communications technology as a case study to focus on the collision problem and to develop an improved scheduling process to mitigate this problem. The Weightless-N utilises a special technique to send multi-copies of the message on different frequencies, which increases the probability of receiving the message correctly. A better performance has been achieved by developing a new frequency selection process, which provides a lower number of collisions than the standard technique for the same number of message copies

Energy efficient active vibration control strategies using electromagnetic linear actuators

Energy efficient current control methods in electromagnetic linear actuators are required to minimize the electrical power requirements imposed by active vibration control strategies. In this paper an efficient bidirectional buck-boost converter is discussed in two scenarios: an active vibration isolation system and an active dynamic vibration absorber (ADVA) using a voice coil motor (VCM) actuator. An electrical analogous circuit of an experimental test platform is used as part of the simulation model. This test platform is based on a vibration shaker that provides the based excitation required for the single Degree of-Freedom (1DoF) vibration model under study. The proposed bidirectional non-isolated buck-boost converter can recover the energy when the VCM acts as a generator and store it for future use. Simulation results prove that this type of topology is far more efficient than linear amplifiers typically used in active vibration control. Within the context of slender structures, this efficient current control method improves the viability of using active vibration control in flexible structures such as beams

Down-regulation of human osteoblast PTH/PTHrP receptor mRNA in end-stage renal failure

Down-regulation of human osteoblast PTH/PTHrP receptor mRNA in end-stage renal failure.BackgroundResistance to the action of parathyroid hormone (PTH) has been demonstrated in end-stage renal failure and is considered to be important in the pathogenesis of secondary hyperparathyroidism. The mechanism of resistance is unknown. However, altered regulation of cellular PTH/PTH-related protein (PTH/PTHrP) receptor (PTH1R) has been assumed to be important.MethodsWe have used in situ hybridization to examine PTH1R mRNA expression by osteoblasts in human bone and have compared the expression in high- and low-turnover renal bone disease, high-turnover nonrenal bone disease (healing fracture callus and Pagetic bone), and normal bone. Bone biopsies were formalin fixed, ethylenediaminetetraacetic acid decalcified, and paraffin wax embedded. A 1.8kb PTH1R cDNA probe, labeled with 35S, was used, and the hybridization signal was revealed by autoradiography. The density of signal over osteoblasts was quantitated using a semiautomated Leica™ image analysis software package.ResultsThe mean density of PTH1R mRNA signal over osteoblasts in renal high-turnover bone was only 36% of that found in nonrenal high-turnover bone (P < 0.05) and 51% of that found in normal bone (P < 0.05). Osteoblast PTH1R mRNA signal in adynamic bone from individuals with diabetes mellitus was 28% of normal bone (P < 0.05) and 54% of that found in renal high-turnover bone (P < 0.05).ConclusionsThese results demonstrate a down-regulation of osteoblast PTH1R mRNA in end-stage renal failure in comparison to normal and high-turnover bone from otherwise healthy individuals, and provide an insight into the mechanisms of “skeletal resistance” to the actions of PTH

Heritability and genetic correlations of heart rate variability at rest and during stress in the Oman Family Study

Introduction:Individual differences in heart rate variability (HRV) can be partly attributed to genetic factors that may be more pronounced during stress. Using data from the Oman Family Study (OFS), we aimed to estimate and quantify the relative contribution of genes and environment to the variance of HRV at rest and during stress; calculate the overlap in genetic and environmental influences on HRV at rest and under stress using bivariate analyses of HRV parameters and heart rate (HR).Methods:Time and frequency domain HRV variables and average HR were measured from beat-to-beat HR obtained from electrocardiogram recordings at rest and during two stress tests [mental: Word Conflict Test (WCT) and physical: Cold Pressor Test (CPT)] in the OFS - a multigenerational pedigree consisting of five large Arab families with a total of 1326 participants. SOLAR software was used to perform quantitative genetic modelling.Results:Heritability estimates for HRV and HR ranged from 0.11 to 0.31 for rest, 0.09-0.43 for WCT, and 0.07-0.36 for CPT. A large part of the genetic influences during rest and stress conditions were shared with genetic correlations ranging between 0.52 and 0.86 for rest-WCT and 0.60-0.92 for rest-CPT. Nonetheless, genetic rest-stress correlations for most traits were significantly smaller than 1 indicating some stress-specific genetic effects.Conclusion:Genetic factors significantly influence HRV and HR at rest and under stress. Most of the genetic factors that influence HRV at rest also influence HRV during stress tests, although some unique genetic variance emerges during these challenging conditions

H2S biosynthesis and catabolism: new insights from molecular studies

Hydrogen sulfide (H2S) has profound biological effects within living organisms and is now increasingly being considered alongside other gaseous signalling molecules, such as nitric oxide (NO) and carbon monoxide (CO). Conventional use of pharmacological and molecular approaches has spawned a rapidly growing research field that has identified H2S as playing a functional role in cell-signalling and post-translational modifications. Recently, a number of laboratories have reported the use of siRNA methodologies and genetic mouse models to mimic the loss of function of genes involved in the biosynthesis and degradation of H2S within tissues. Studies utilising these systems are revealing new insights into the biology of H2S within the cardiovascular system, inflammatory disease, and in cell signalling. In light of this work, the current review will describe recent advances in H2S research made possible by the use of molecular approaches and genetic mouse models with perturbed capacities to generate or detoxify physiological levels of H2S gas within tissue

Courses for the NDT industry

In 2005 the BINDT approached the University of Northampton with a view to developing an academic qualification that could be gained by people in the NDT industry specifically in the UK. A proposal was made to develop a Foundation Degree in NDT, which would be distance-taught and would be closely linked to the practical certification that NDT practitioners have to undertake. Over the next two years the material was developed and the course started in September 2007. Since then there has been a steady increase in student numbers, and in 2009 the first group of students completed the course. In 2009 a distance learning top-up BSc was approved and in 2010 it recruited the first cohort of students. The BSc was designed in consultation with the existing Foundation Degree students and members of the BINDT. In an international context, we have a small but growing number of overseas students. In addition, we have produced a campus-based version of the BSc top-up which will be admitting its first cohort of students in 2013. We conclude that the courses have been successful due to the close relationship with the relevant industry body. Our aim is to expand on the range of NDT and condition monitoring courses and maintain our unique position in this are