Galling wear detection and measurement in sheet metal forming

Galling wear of sheet metal stamping tooling is an expensive issue for sheet metal forming industries. Forming of high strength steels, particularly in the automotive industry, has led to accelerated tool wear rates. These wear rates lead to product quality and die maintenance issues, making galling wear an expensive issue for automotive manufacturers and the sheet metal forming industries in general. Process monitoring allows for the continuous monitoring of tooling condition so that wear development can be detected. The aim of this investigation was to develop an in-depth understanding of the relationship between punch force variation and wear for implementation in future process monitoring regimes. To achieve this aim, the effect of wear and other friction influencing factors on punch force signatures were investigated. This required the development of an accurate method for quantifying galling wear severity so that the relationship between galling wear progression and punch force signature variation could be quantified. Finally, the specific effects of wear and friction conditions on the punch force signatures were examined. An initial investigation using a statistical pattern recognition technique was conducted on stamping force data to determine if the presence of galling wear on press tooling effected punch force variation. Galling wear on tooling, changes in lubrication type, and changes in blank holder pressure were all found to effect variation in punch force signatures shape. A new galling wear severity measurement methodology was developed based on wavelet analysis of 2D surface roughness profiles that accurately provided an indication of the location and severity of galling wear damage. Using the new method for quantifying galling wear severity in the relationship between punch force variation and galling wear progression was investigated, and a strong linear relationship was found. Finally, two prominent vii forms of punch force signature shape variation were linked to friction conditions driven by wear, lubrication, and blank holder pressure. This work describes and quantifies the relationship between galling wear and punch force signature variation. A new methodology for accurate measurement of galling wear severity is presented. Finally, specific forms of punch force signature variation are linked to different friction conditions. These results are critical for future implementation of punch force based galling wear process monitoring and a significant reduction in costs for the metal forming industries

LOAD NOISE INCREASE OF TRANSFORMERS BY LOAD HARMONICS

Electrical power and distribution transformers in field operation regularly show significant deviation in the load noise level in comparison to the sound measurements in the test field of the manufacturer where controlled and standardised measurement conditions apply. The main reason therefore are (a) the changed acoustical ambient conditions on-site caused by sound reflection and diffraction effects of nearby obstacles; (b) changed structural and acoustical resonances, and (c) the different principal operation conditions on-site. Whereas at the factory tests a pure sinusoidal current with short-circuited secondary winding is applied for load noise determination, transformers on-site operate at changed load power factors (phase angle between voltage and load-current), loading beyond the rated power (overload, partial load) as well as harmonics in the load-current. Harmonic components in the power grid are caused primarily by nonlinear loads and by the nonlinear transfer characteristic of the power grid. Any electrical device which shows a nonlinear consumption of active power or a nonlinear change of the source impedance draws a distorted current waveform even if the supply voltage is sinusoidal. With the growing use of electrical and electronic devices, distorted waveforms in power supply grid by harmonics have been largely increased within the past years. Devices like variable speed drives, six-pulse bridge rectifiers used in power electronics, and discharge lamps draw a non-sinusodial but pulsating current. Whereas most electric devices generate solely odd harmonics, some devices with fluctuating power consumption generate odd, even and also interharmonic currents [1]. Load noise is generated by electromagnetic forces acting on transformer windings. The forces are proportional to the square of the load-current (Section 2.2). This quadratic response behaviour generates winding vibrations at frequencies beyond the power frequency. In case of harmonics in the load-current, the resulting magnetic force and noise components have harmonics as well- with a more complex frequency spectrum. The related increase of the load noise level must be considered in the estimation of the total noise level of transformers under real load conditions. The question arise how to predict the resulting noise level at these loading conditions to guarantee the maximum allowed sound level at the transformer site as requested by legislative regulations or the owners specification. Starting from basic principles, we describe and quantify the generation of harmonics in winding forces, winding vibrations and load noise of electrical transformers caused by load harmonics. A calculation scheme for a fast and practically accurate estimation of the increase in the load noise level for a given load spectrum presented. The effects of A-weighting and frequency-dependent sound radiation efficiency of transformers to the total noise level are discussed. Finally, three practical examples are given

Methods for evaluating cervical range of motion in trauma settings

Immobilisation of the cervical spine is a common procedure following traumatic injury. This is often precautionary as the actual incidence of spinal injury is low. Nonetheless, stabilisation of the head and neck is an important part of pre-hospital care due to the catastrophic damage that may follow if further unrestricted movement occurs in the presence of an unstable spinal injury. Currently available collars are limited by the potential for inadequate immobilisation and complications caused by pressure on the patient's skin, restricted airway access and compression of the jugular vein. Alternative approaches to cervical spine immobilisation are being considered, and the investigation of these new methods requires a standardised approach to the evaluation of neck movement. This review summarises the research methods and scientific technology that have been used to assess and measure cervical range of motion, and which are likely to underpin future research in this field. A systematic search of international literature was conducted to evaluate the methodologies used to assess the extremes of movement that can be achieved in six domains. 34 papers were included in the review. These studies used a range of methodologies, but study quality was generally low. Laboratory investigations and biomechanical studies have gradually given way to methods that more accurately reflect the real-life situations in which cervical spine immobilisation occurs. Latterly, new approaches using virtual reality and simulation have been developed. Coupled with modern electromagnetic tracking technology this has considerable potential for effective application in future research. However, use of these technologies in real life settings can be problematic and more research is needed. © 2012 Voss et al.; licensee BioMed Central Ltd

The secondary structure of apolipoprotein A-I on 9.6-nm reconstituted high-density lipoprotein determined by EPR spectroscopy.

Apolipoprotein A-I (ApoA-I) is the major protein component of high-density lipoprotein (HDL), and is critical for maintenance of cholesterol homeostasis. During reverse cholesterol transport, HDL transitions between an array of subclasses, differing in size and composition. This process requires ApoA-I to adapt to changes in the shape of the HDL particle, transiting from an apolipoprotein to a myriad of HDL subclass-specific conformations. Changes in ApoA-I structure cause alterations in HDL-specific enzyme and receptor-binding properties, and thereby direct the HDL particle through the reverse cholesterol transport pathway. In this study, we used site-directed spin label spectroscopy to examine the conformational details of the ApoA-I central domain on HDL. The motional dynamics and accessibility to hydrophobic/hydrophilic relaxation agents of ApoA-I residues 99-163 on 9.6-nm reconstituted HDL was analyzed by EPR. In previous analyses, we examined residues 6-98 and 164-238 (of ApoA-I's 243 residues), and combining these findings with the current results, we have generated a full-length map of the backbone structure of reconstituted HDL-associated ApoA-I. Remarkably, given that the majority of ApoA-I's length is composed of amphipathic helices, we have identified nonhelical residues, specifically the presence of a β-strand (residues 149-157). The significance of these nonhelical residues is discussed, along with the other features, in the context of ApoA-I function in contrast to recent models derived by other methods

A Guide to Knowing Your Rights with the Police and Getting Out of Jail: Booklet 2

ArchCity Defenders created a self-advocating guide for people to use if they have an encounter with the police, jail or the courts

Fractional-Order Partial Cancellation of Integer-Order Poles and Zeros

The key idea of this contribution is the partial compensation of non-minimum phase zeros or unstable poles. Therefore the integer-order zero/pole is split into a product of fractional-order pseudo zeros/poles. The amplitude and phase response of these fractional-order terms is derived to include these compensators into the loop-shaping design. Such compensators can be generalized to conjugate complex zeros/poles, and also implicit fractional-order terms can be applied. In the case of the non-minimum phase zero, its compensation leads to a higher phase margin and a steeper open-loop amplitude response around the crossover frequency resulting in a reduced undershooting in the step-response, as illustrated in the numerical example.publishedVersio

Hypervelocity Impact Ionized TOFMS Experiments with Amino Acid Mixtures in Ice Targets

Time of Flight Mass Spectrometry (TOFMS) has long been an important tool for understanding the molecular composition of substances, and forms the basis of flight instruments in spacecraft exploring the solar system. Spacecraft carrying TOFMS instruments will return a tremendous amount of information about the composition of cosmic dust and ejecta from planets, moons, comets, and asteroids. There are outstanding questions, however, on the details of hypervelocity dust measurements, because the vast majority of laboratory TOFMS experiments thus far have been based on laser or electron ionization rather than hypervelocity impact ionization, which is the mechanism used in flight instruments. This thesis describes a series of experiments which (1) develop methods for creating unique frozen targets from water and water-soluble compounds, and (2) explore the resulting spectra from known mixtures of two amino acids, as a proof-of-principle for extracting mixture data from planetary samples. The target-preparation methods proved capable of creating a uniform frozen target surfaces of mixed solutions, exceeding the performance of previous approaches. The followup experiments took advantage of these methods to create targets of various mixtures of the amino acids Arginine and Lysine and test their response to hypervelocity impacts using the TOFMS system. It is shown that relative concentrations of these amino acids can be recovered from TOFMS in the low impact velocity regime using a method of line fitting. The target and amino acid mixtures experiments produced promising results and show that by using these methods other experiments could be carried out in the same way to reinforce our understanding of what we may see from spacecraft-mounted TOFMS systems.</p

C++ for Heterogeneous Programming: oneAPI (DPC++ and oneTBB)

This tutorial provides hands-on experience programming CPUs, GPUs and FPGAs using a unified, standards-based programming model: oneAPI. oneAPI includes a cross-architecture language: Data Parallel C++ (DPC++). DPC++ is an evolution of C++ that incorporates the SYCL language with extensions for Unified Shared Memory (USM), ordered queues and reductions, among other features. oneAPI also includes libraries for API-based programming, such as domain-specific libraries, math kernel libraries and Threading Building Blocks (TBB). The main benefit of using oneAPI over other heterogeneous programming models is the single programming language approach, which enables one to target multiple devices using the same programming model, and therefore to have a cleaner, portable, and more readable code. In the current heterogeneous era, it is still challenging for developers to match computations to accelerators and to coordinate the use of those accelerators in the context of their larger applications. Therefore, this tutorial’s main goal is not just teaching oneAPI as an easier approach to target heterogeneous platforms, but also to convey techniques to map applications to heterogeneous hardware paying attention to the scheduling and mapping problems (how to achieve load balance and which regions of the application are more suitable to each particular device).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech