Penetration Thresholds Research Articles

Penetration Thresholds of Porcine Limbs for Low Sectional Density Projectiles in High-Rate Impact.

With similar prevalence to injuries from fires, stings, and natural disasters, soft tissue injuries may occur from fireworks, industrial accidents, or other explosives. Surgeons are less familiar with treating high-velocity penetration from small debris, which may increase the chance of infection and subsequent fatality. Penetration risk curves have been developed to predict V50, the velocity with 50% probability of penetration, for various sized projectiles. However, there has been limited research using nonmetallic materials to achieve lower density projectiles less than 1 g cm-2, such as sand or rocks. To emulate the size and density of these energized particles, 14 ball bearings of stainless steel, silicon nitride, or Delrin acetal plastic ranging from 1.59 mm (1/16") to 9.53 mm (3/8") with sectional densities between 0.3 g cm-2 and 5 g cm-2 were launched toward porcine legs at a range of velocities to determine the penetration thresholds. High-speed videography was captured laterally at 40 kHz and impact velocity was captured using a physics-based tracking software. A generalized linear model with repeated measures and a logit link function was used to predict probability of penetration for each projectile. A total of 600 impacts were conducted to achieve at least 15 penetrating impacts for each projectile over a range of velocities. Higher impact velocities were required to penetrate the skin as sectional density of the projectile decreased, and the relationship between velocity and sectional density exhibited an exponential relationship (V50, $ = 184.6*S{D^{ - 0.385}}$, R2 = 0.95) with substantial change for nonlinearity in sectional densities ranging from 0.3 g cm-2 to 1 g cm-2. Compared to previous studies, the empirical relationship was consistent in the linear region (2-5 g cm-2), and novel experimentation filled in the gaps for sectional densities less than 1 g cm-2, which expressed more nonlinearity than previously estimated. For low-density projectiles with diameters of 1.59 (1/16") or 3.18 (1/8"), 32 impacts were lodged into the epidermis but did not penetrate through the dermis; however, penetration was defined as displacement into or through the dermis. These experimental results may be used to develop and validate finite element simulations of low-density projectile impacts to address complex, multivariate loading conditions for the development of protective clothing to reduce wounding and subsequent infection rates.

Female unemployment and the procedure that a woman has to go through to start a business: microfinance policy thresholds

PurposeThis study aims to examine how the starting of business by females can be promoted by assessing critical levels of microfinance institutions (MFIs) penetration that policymakers must endeavor to maintain and/or attain in order for female unemployment not to represent a constraint in the doing of business. A constraint in doing business is understood in terms of the procedure that a woman has to go through to start a business.Design/methodology/approachThe focus of the study is on 44 countries in Sub-Saharan Africa for the period 2004–2018, while the empirical evidence is based on interactive quantile regressions.FindingsThe following findings are established. The validity of tested hypotheses is exclusively apparent in the lowest and highest quantiles of the conditional distribution of the procedure women have to go through to start a business. MFI penetration levels needed to reverse the unfavorable incidence of female unemployment in doing business are provided. These are minimum MFIs penetration thresholds that are required in order for female unemployment not to negatively affect the procedure that a woman should go through to start a business.Originality/valueThe study complements the extant literature by assessing critical microfinance penetration levels that are needed to promote female doing of business, contingent on existing levels of female doing of business.

Error-field penetration thresholds in ohmically heated ITER and SPARC plasmas

The critical n = 1, n = 2, and n = 3 error-field amplitudes needed to trigger error-field penetration in ITER and SPARC, steady-state, ohmically heated plasmas are calculated using a standard asymptotic matching approach. The calculation incorporates plasma impurities, trapped particles, the bootstrap current, and neoclassical poloidal flow-damping. The energy confinement time is specified by the neo-Alcator scaling law in the low-density linear Ohmic confinement (LOC) regime and by the ITER-89P L-mode scaling law in the high-density saturated Ohmic confinement (SOC) regime. The response of the plasma in the inner region is calculated using a linearized version of the four-field model. At the normal operating electron number density, diamagnetic levels of rotation are found to be sufficient to protect ITER and SPARC ohmically heated plasmas from m=2/n=1 error-field penetration. On the other hand, SPARC, and especially ITER, ohmically heated plasmas may be vulnerable to n > 1 error-field penetration. ITER and SPARC ohmically heated plasmas are also slightly more susceptible to error-field penetration when the electron fluid at the rational surface rotates in the ion diamagnetic direction, rather than the electron diamagnetic direction. At electron number densities that are sufficiently low that the plasma lies in the LOC confinement regime, the error-field penetration threshold increases with increasing density. However, as soon as the electron number density becomes large enough that the plasma enters the SOC regime, the increase in the error-field penetration threshold with increasing density levels off.

Study of the spectrum effect on the threshold of resonant magnetic perturbation penetration on J-TEXT

The spectrum effect on the penetration of resonant magnetic perturbation (RMP) is studied with upgraded in-vessel RMP coils on J-TEXT. The poloidal spectrum of the RMP field, especially the amplitudes of 2/1 and 3/1 components, can be varied by the phase difference between the upper and lower coil rows, Δϕ = ϕ top−ϕ bottom, where ϕ top and ϕ bottom are the toroidal phases of the n = 1 field of each coil row. The type of RMP penetration is found to be related to Δϕ, including the RMP penetration of either 2/1 or 3/1 RMP and the successive penetrations of 3/1 RMP followed by the 2/1 RMP. For cases with penetration of only one RMP component, the penetration thresholds measured by the corresponding resonant component are close for various Δϕ. However, the 2/1 RMP penetration threshold is significantly reduced if the 3/1 locked island is formed in advance. The changes in the rotation profile due to 3/1 locked island formation could partially contribute to the reduction of the 2/1 thresholds.

Fibre–Wood Laminate Biocomposites: Seawater Immersion Effects on Flexural and Low Energy Impact Properties

The present paper explores a new concept of a hybrid eco-composite by substituting the natural fibre plies with thin wood veneers. The new composite, named Fibre–Wood Laminate (FWL), is inspired by fibre–metal laminate materials. The studied FWL configuration consisted of a single thin pinewood veneer at each of the outer layers of a flax woven fabric reinforced bio-epoxy composite manufactured by infusion. Three-point bending results showed that wood veneer gives a highly anisotropic nature to the FWL. In the best case, with the grain of the wood at 0°, the stiffness and the strength increased by 28 and 41%, respectively, but reduced the strain-at-break by 27% compared to the flax fibre reinforced bio-epoxy (FFRB). The penetration and perforation energy thresholds and the peak force of the FWL obtained by falling weight impact tests were 32, 29, and 31% lower than those of the FFRB, respectively. This weakening was due to using single wood veneers, so the challenge for improving impact properties will be to explore thicker FWLs with different stacking sequences and orientations. The effect of immersing the FWL in seawater also showed considerable differences. The epoxy matrix filled the cellular structure of the wood veneers, creating a barrier effect and reducing the amount of water absorbed by the flax fibres.

The mobile phone in governance for environmental sustainability in Sub-Saharan Africa

PurposeIn this study, we assess how the mobile phone can be leveraged upon to improve the role of governance in environmental sustainability in 44 Sub-Saharan African countries.Design/methodology/approachThe Generalised Method of Moments is used to establish policy thresholds. A threshold is a critical mass or level of mobile phone penetration at which the net effect of governance on carbon dioxide (CO2) emissions changes from positive to negative.FindingsMobile phone penetration thresholds associated with negative conditional effects are: 36 (per 100 people) for political stability/no violence; 130 (per 100 people) for regulation quality; 146.66 (per 100 people) for government effectiveness; 65 (per 100 people) for corruption-control and 130 (per 100 people) for the rule of law. Practical and theoretical implications are discussed.Originality/valueThe study provides thresholds of mobile phone penetration that are critical in complementing governance dynamics to reduce CO2 emissions.

Mechanical performance and damage mechanisms of thin rectangular carbon/ Elium® tubular thermoplastic composites under flexure and low-velocity impact

Hollow thin composite tubular structures are widely used in many industrial applications and there is a growing need to innovate both the manufacturing process which is suitable for mass production as well as the material aspects to improvise the mechanical properties and the weight. The current research presents a detailed study on manufacturing thin hollow woven carbon fibre (WC)/Elium® (EL) rectangular tubular structures. Bladder resin transfer moulding process optimization study is carried out and the moldability zones were defined. A detailed experimental investigation was carried out to understand the impact and flexure properties of woven carbon (WC) tubular configurations with Elium® (EL) and Epoxy (EP) matrix system. Impact tests were performed at 6 different energies to derive the energy profiling diagrams by studying the penetration and preformation thresholds. WC/EL tubular configuration has shown a maximum 12.5% increase in peak load and 55% increase in absorbed energy as compared to WC/EP composite, respectively. The WC/EL composite tubes have shown similar or better results in terms of bending strength (10% higher) and there was a noticeable increase in deformation owing to the extended plasticity behaviour of acrylic thermoplastic resin compared to WC/EP composites. The rationale and underlying reasons for the differences in the mechanical performance and failure mechanisms for both the tubes tested in impact and flexural are studied with the help of high-speed camera examination and microscopic study and are deliberated in this paper.

Green Synthesis, Antioxidant, and Plant Growth Regulatory Activities of Novel α-Furfuryl-2-alkylaminophosphonates.

A series of novel α-furfuryl-2-alkylaminophosphonates have been efficiently synthesized from the one-pot three-component classical Kabachnik–Fields reaction in a green chemical approach by addition of an in situ generated dialkylphosphite to Schiff’s base of aldehydes and amines by using environmental and eco-friendly silica gel supported iodine as a catalyst by microwave irradiation. The advantage of this protocol is simplicity in experimental procedures and products were resulted in high isolated yields. The synthesized α-furfuryl-2-alkylaminophosphonates were screened to in vitro antioxidant and plant growth regulatory activities and some are found to be potent with antioxidant and plant growth regulatory activities. These in vitro studies have been further supported by ADMET (absorption, distribution, metabolism, excretion, and toxicity), quantitative structure–activity relationship, molecular docking, and bioactivity studies and identified that they were potentially bound to the GLN340 amino acid residue in chain C of 1DNU protein and TYR597 amino acid residue in chain A of 4M7E protein, causing potential exhibition of antioxidant and plant growth regulatory activities. Eventually, title compounds are identified as good blood–brain barrier (BBB)-penetrable compounds and are considered as proficient central nervous system active and neuroprotective antioxidant agents as the neuroprotective property is determined with BBB penetration thresholds.

The Mobile Phone in Governance for Environmental Sustainability in Sub-Saharan Africa

In this study, we assess how the mobile phone can be leveraged upon to improve the role of governance in environmental sustainability in 44 Sub-Saharan African countries. The Generalised Method of Moments is used to establish policy thresholds. A threshold is a critical mass or level of mobile phone penetration at which the net effect of governance on Carbon dioxide (CO2) emissions changes from positive to negative. Mobile phone penetration thresholds associated with negative conditional effects are: 36 (per 100 people) for political stability/no violence; 130 (per 100 people) for regulation quality; 146.66 (per 100 people) for government effectiveness; 65 (per 100 people) for corruption-control and 130 (per 100 people) for the rule of law. Practical and theoretical implications are discussed. The study provides thresholds of mobile phone penetration that are critical in complementing governance dynamics to reduce CO2 emissions.

Toroidal field and q95 scalings on error field penetration in EAST

Toroidal field and q95 scalings of error field penetration are investigated with n = 1 resonant magnetic perturbation coil in EAST. The toroidal field scalings of error field penetration thresholds under fixed q95 are about in both ohmically and lower hybrid wave heated plasmas, where br21 is the vacuum error field at the q = 2/1 rational surface and BT is the toroidal field. These scalings indicate a favorable tolerance on error field in ITER. To make clear the underlying physics on toroidal field scaling, the theoretical analysis is given. By subtituting penetration related scaling parameters into the theory, the obtained theoretical scalings are consistent with the experimental observations using the vacuum penetration thresholds. To further investigate penetration threshold in larger operation region, the q95 scaling on penetration threshold with has also been observed. The rational surface radius rs and magnetic shear s, which are crucial to q95 scaling, are included in the theoretical analysis. The theoretical analysis is also consistent with the experimental scalings using the vacuum penetration thresholds. Moreover, the obtained theoretical scalings are easy to compare with experimental scalings. These theoretical analyses will stimulate the extrapolation of error field tolerance towards future reactors.

Empirical scaling of the n = 2 error field penetration threshold in tokamaks

This paper presents a multi-machine, multi-parameter scaling law for the n = 2 core resonant error field threshold that leads to field penetration, locked modes, and disruptions. Here, n is the toroidal harmonic of the non-axisymmetric error field (EF). While density scalings have been reported by individual tokamaks in the past, this work performs a regression across a comprehensive range of densities, toroidal fields, and pressures accessible across three devices using a common metric to quantify the EF in each device. The metric used is the amount of overlap between an EF and the spectrum that drives the largest linear ideal MHD resonance, known as the "dominant mode overlap". This metric, which takes into account both the external field and plasma response, is scaled against experimental parameters known to be important for the inner layer physics. These scalings validate non-linear MHD simulation scalings, which are used to elucidate the dominant inner layer physics. Both experiments and simulations show that core penetration thresholds for EFs with toroidal mode number n = 2 are of the same order as the n = 1 thresholds that are considered most dangerous on current devices. Both n = 1 and n = 2 thresholds scale to values within the ITER design tolerances, but data from additional devices with a range of sizes are needed in order to increase confidence in quantitative extrapolations of n = 2 thresholds to ITER.

Tephra cushioning of ballistic impacts: Quantifying building vulnerability through pneumatic cannon experiments and multiple fragility curve fitting approaches

Ballistic projectiles are the most frequently lethal volcanic hazard close to the vent. Recent eruptions of Ontake in 2014 and Kusatsu-Shirane in 2018 showed that un-reinforced, timber-framed buildings - those typically considered highly vulnerable to the dangerous penetration of ballistics - provided life-saving shelter from ballistic impact. Modelled kinetic energies of some non-penetrating impacts were an order of magnitude above expected penetration thresholds. It has been hypothesised that a pre-existing layer of tephra on the roofs cushioned impacts. To quantitatively test this, and improve our understanding of how buildings respond to projectile impacts, we used a pneumatic cannon to simulate block impacts to clay tiles and reinforced concrete roof slabs covered with tephra layers 0–20 cm thick. Substantially higher impact energies were resisted when tephra was present with 5 cm of tephra approximately tripling the penetration threshold of both building materials. Fragility curves, which relate ballistic hazard intensity with the probability of building damage, were developed from our experimental data following three curve fitting approaches: generalised link models, cumulative link models and data binning. A key benefit of these approaches is that confidence in these curves can be robustly quantified from the data – the first time that this has been attempted for volcanic fragility curves. This study shows how the extent of building damage can be strongly influenced by the sequence of volcanic hazards and provides an example of proactive risk management through testing of physical mitigation strategies in a laboratory environment.

Remittances, ICT and doing business in Sub-Saharan Africa

PurposeThe purpose of this paper is to examine how linkages between information and communication technology (ICT) and remittances affect the doing of business.Design/methodology/approachThe focus is on a panel of 49 Sub-Saharan African (SSA) countries for the period 2000–2012. The empirical evidence is based on the generalized method of moments.FindingsWhile the authors establish some appealing results in terms of net negative effects on constraints to the doing of business (i.e. time to start a business and time to pay taxes), some positive net effects are also apparent (i.e. number of start-up procedures, time to build a warehouse and time to register a property). The authors also establish ICT penetration thresholds at which the unconditional effect of remittances can be changed from positive to negative, notably: for the number of start-up procedures, an internet level of 9.00 penetration per 100 people is required, while for the time to build a warehouse, a mobile phone penetration level of 32.33 penetration per 100 people is essential. Practical and theoretical implications are discussed.Originality/valueTo the best of the authors’ knowledge, this is the first study to assess linkages between ICT, remittances and doing business in SSA.

Analysis of impact energy absorption by lightweight aramid structures

This paper presents and analyses the behaviour of aramid composite plates subjected to low and medium impact energies. In order to study the material behaviour under impact loading, experimental tests have been performed using a drop-weight tower and a pneumatic gas gun within the range of impact energies (20J<Eimp<600J). The plates are impacted by hemispherical impactor and spherical projectile for drop-weight and impact tests, respectively. The influence of areal density is also evaluated in terms of absorption energy. Energy Profile Diagrams (EPD) are used to identify the penetration and perforation thresholds enabling the definition of the no-penetration, penetration and perforation zones. The results revealed that there is a greater energy absorption capacity in thin plate than in thick plate for low impact energy values. However, areal density is relevant in the energy absorption capacity for high impact energy values.

Density scaling on n = 1 error field penetration in ohmically heated discharges in EAST

Density scaling of error field penetration in EAST is investigated with different n = 1 magnetic perturbation coil configurations in ohmically heated discharges. The density scalings of error field penetration thresholds under two magnetic perturbation spectra are and , where br is the error field and ne is the line averaged electron density. One difficulty in understanding the density scaling is that key parameters other than density in determining the field penetration process may also be changed when the plasma density changes. Therefore, they should be determined from experiments. The estimated theoretical analysis ( in lower density region and in higher density region), using the density dependence of viscosity diffusion time, electron temperature and mode frequency measured from the experiments, is consistent with the observed scaling. One of the key points to reproduce the observed scaling in EAST is that the viscosity diffusion time estimated from energy confinement time is almost constant. It means that the plasma confinement lies in saturation ohmic confinement regime rather than the linear Neo-Alcator regime causing weak density dependence in the previous theoretical studies.

Remittances, ICT and Doing Business in Sub-Saharan Africa

Purpose – This study examines how linkages between information and communication technology (ICT) and remittances affect the doing of business. Design/methodology/approach – The focus is on a panel of 49 sub-Saharan African countries for the period 2000-2012. The empirical evidence is based on Generalised Method of Moments. Findings – While we establish some appealing results in terms of net negative effects on constraints to the doing of business (i.e. time to start a business and time to pay taxes), some positive net effects are also apparent (i.e. number of start-up procedures, time to build a warehouse and time to register a property). We also establish ICT penetration thresholds at which the unconditional effect of remittances can be changed from positive to negative, notably: (i) for the number of start-up procedures, an internet level of 9.00 penetration per 100 people is required while (ii) for the time to build a warehouse, a mobile phone penetration level of 32.33 penetration per 100 people is essential. Practical and theoretical implications are discussed. Originality/value – To the best of our knowledge, this is the first study to assess linkages between ICT, remittances and doing business in Sub-Saharan Africa.

Mobile Phone Innovation and Environmental Sustainability in Sub-Saharan Africa

This study investigates how the mobile phone can complement knowledge diffusion in order to influence CO2 emissions in 44 Sub-Saharan African countries for the period 2000-2012. The empirical evidence is based on Generalised Method of Moments. Three knowledge diffusion variables representing three of the four pillars of the World Bank’s Knowledge Economy Index are employed: educational quality, information and communication technology (ICT) and scientific output. Six CO2 emission variables are used, namely: CO2 per capita, CO2 from electricity and heat, CO2 from liquid fuel, CO2 from manufacturing and construction, CO2 from transport and CO2 intensity. In the assessments, a decreasing tendency in these variables translates into positive conditions for environmental sustainability. Based on net effect from complementarities, the following findings are established. First, the mobile phone complements education to have a net negative effect on CO2 emissions per capita and CO2 emissions from the consumption of liquid fuel. Second, where some positive net effects of knowledge diffusion are apparent, corresponding marginal effects are negative. Corresponding mobile phone penetration thresholds at which the positive net effects on CO2 emissions can be dampened and reversed are largely within policy range. Practical and theoretical implications are discussed.

Non-destructive evaluation of damage modes in nanocomposite foam-core sandwich panel subjected to low-velocity impact

Abstract This research studied the effect of multi-walled carbon nanotubes (MWCNTs) on the internal and external damages of foam-core sandwich panels with kevlar fiber reinforced epoxy face sheets subjected to a low-velocity impact. The sandwich panels were subjected to six levels of energy. Energy profile diagrams (EPDs) were plotted to determine the rebounding, penetration and perforation thresholds of the sandwich panels. Non-destructive evaluation methods have been employed for detecting and measuring damage size of the sandwich panels using X-ray radiography and active infrared thermography. The results show that MWCNTs can improve the absorbed energy and penetration threshold of the foam-core sandwich panels.

Observation of spectrum effect on the measurement of intrinsic error field on EAST

Intrinsic error field on EAST is measured using the ‘compass scan’ technique with different n = 1 magnetic perturbation coil configurations in ohmically heated discharges. The intrinsic error field measured using a non-resonant dominated spectrum with even connection of the upper and lower resonant magnetic perturbation coils is of the order and the toroidal phase of intrinsic error field is around . A clear difference between the results using the two coil configurations, resonant and non-resonant dominated spectra, is observed. The ‘resonant’ and ‘non-resonant’ terminology is based on vacuum modeling. The penetration thresholds of the non-resonant dominated cases are much smaller than that of the resonant cases. The difference of penetration thresholds between the resonant and non-resonant cases is reduced by plasma response modeling using the MARS-F code.

Influence of seawater immersion in low energy impact behavior of a novel colombian fique fiber reinforced bio-resin laminate

This experimental work is aimed at the influence of seawater immersion in low impact energy behavior of a novel Colombian fique fiber reinforced bio-resin laminate. Such material was manufactured by vacuum infusion. The specimens were immersed in seawater during a bioactivity period of six months. Low energy impact tests were performed in order to obtain the penetration and perforation threshold according to energy profiles. The damage extent was characterized by means of Ultrasonics. Tensile stress tests were also performed and the breaking surfaces were analyzed by Scanning Electron Microscopy. The results revealed that the new biocomposite, after seawater immersion, has higher penetration and perforation thresholds than the biocomposite without immersion. Tensile test results show stiffness lost and increase of elongation at break. This behavior of the immersed biocomposite is due to a plasticization process of the material.