Debris Analysis Research Articles

Investigation of Kerosene used as Fire Accelerant Remaining on Different Kinds of Fabrics

In arson cases, the detection and identification of fire accelerants is of high importance for elucidation of such crimes. The present study aims to investigate the remaining fraction of kerosene hydrocarbons impregnated on four kinds of textiles (nylon, polyester, wool and cotton). The volatile fraction was collected by SPME on non-burnt and burnt samples at successive times (0, 0.5, 1, 2 and 4 h.), then analyzed by GC-MS. Among the 27 characteristic compounds identified in kerosene, aromatic hydrocarbons were the predominant components, but their evaporation was faster than alkanes in unburnt textiles. Also, in the case of non-burnt samples, the total amount of kerosene residues was higher in synthetic tissues than in natural materials. After burning the different kinds of impregnated textiles, 22 hydrocarbons were detected with a decreasing amount over time, while the concentration of linear alkanes remained higher during the sampling time. All the partially burnt samples displayed much less kerosene residues than in the same unburnt samples. Unlike the non-burnt samples, the profile of kerosene amount as function of time was very similar on the four investigated kinds of fabrics after burning. These results and the proposed procedure should help forensic investigators in the field of fire debris analysis, in arson cases.

Attitude analysis of space debris using SLR and light curve data measured with single-photon detector

Attitude is the important parameter for active debris removal and collision avoidance. This paper deduced the spin axis orientation and spin period of the rocket body, CZ-3B R/B (NORAD ID 38253), using the satellite laser ranging and light curve data measured with single-photon detector at Graz station. The epoch method and LC & SLR residuals fitting were combined to determine these values. The derived right ascension angle was around 220°, the declination angle was near 64° and the sidereal period was calculated to be 117.724 s, for 2017-07-03. The results derived from the two distinct methods were mutually validated. Rocket bodies are a major contributor to space debris and this work provides a reference for attitude determination and attitude modelling.

INTEGRATION AND OPTIMIZATION OF VARIOUS CONDITIONS MONITORING METHOD

Condition Monitoring technique acts as revolutionary mechanism because of effective, quick, reliable and cost effective application to uphold, maximize, optimize uninterrupted operation of high end equipment’s, in particular and all operating equipment’s, in general specially in power plant. Various methods are been adopted in this technique in which vibration analysis, wear debris analysis, thermography etc., are most common, widely recognized and in practice for carrying out condition monitoring program. These methods acts as preventive and proactive approach in identifying wear in machines and diagnose fault occurred in the machinery. Generally these condition monitoring techniques are isolated, carried out independently by respective departments, analyzed separately without establishing correlation between these techniques, leading to generation of separate reports for each technique. This leads to only a part of turbine faults typically get diagnosed. Therefore integration of these techniques can provide greater, deeper, and more reliable quick information leading to effective diagnosis of turbine in more accurate way. This paper deals with integrations and optimization of all various condition monitoring techniques that can be carried out simultaneously on turbine leading to early detection of problem and proper diagnosis to be carried out resulting in minimizing operating cost, avoid unplanned breakdown, and to maintain uninterrupted operation of turbine.

Tribological Property Investigation of Self-Lubricating Molybdenum-Based Zirconia Ceramic Composite Operational at Elevated Temperature

Abstract Three mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) with 0.5 wt% of magnesium oxide (MgO) and 6 wt% of molybdenum (Mo) were prepared by the pressureless sintering process, and the friction and wear behavior of the ceramic composite were studied against the alumina disc. Tribological tests were carried out both at room temperature as well as at an elevated temperature (500 °C). The result revealed that a substantial reduction of ∼50% in the friction coefficient and ∼31% reduction in the wear rate were achieved while 6 wt% Mo was added into the 3Y-TZP matrix operational at 500 °C. No significant tribological influence was observed with the addition of Mo at the normal operating temperature. The minimum coefficient of friction and low specific wear rate were achieved because of the formation of MoO3 in between the mating surfaces at elevated temperature. The worn surfaces were characterized by means of field emission scanning electron microscopy (FESEM). The formation of MoO3 phases was identified by wear debris analysis which was performed with the help of X-ray photoelectron spectroscopy (XPS).

Improvements in a kinetic-based model to predict evaporation of gasoline

Reference collections containing chromatograms of ignitable liquids are widely used in fire debris analysis to aid the identification of any liquid present in the debris. Most reference collections also include chromatograms of ignitable liquids evaporated to different levels to account for chemical changes as a result of evaporation during the fire. Previous work in our laboratory demonstrated the potential of a kinetic-based model to predict chromatograms corresponding to evaporated liquids, thereby eliminating the need for experimental evaporations. Our initial work indicated the need to improve accuracy in predicting chromatograms corresponding to evaporated gasoline, which is the focus in the current work.Three gasoline samples were experimentally evaporated to 50%, 70%, and 90% by mass and analyzed by gas chromatography-mass spectrometry (GC–MS). Modifications to the instrument method, including elimination of the solvent delay and subtraction of background interferences, resulted in improved correlation between predicted and experimental chromatograms at each evaporation level. Modification of the method used to calculate the total fraction of the liquid remaining offered further improvement in predictive accuracy across all three evaporation levels. Application of the model to generate a reference collection of predicted chromatograms for gasoline and other ignitable liquids was also demonstrated, with maximum Pearson product-moment correlation (PPMC) coefficients ranging from 0.937 to 0.991 for comparisons of predicted and experimental gasoline. The model improvements reported here provide a method by which predicted chromatograms corresponding to any evaporation level of gasoline can be generated accurately, saving time and resources in generating reference collections for fire debris applications.

Aluminum nanoparticle plasma formation for high-order harmonic generation

We demonstrate the efficient high-order harmonic generation (HHG) of 35 fs pulses from the nanoparticle (NP)–containing plasmas produced during laser ablation of aluminum (Al) target using picosecond and nanosecond pulses. The role of NPs in the enhancement of harmonic yield is discussed. To achieve the maximal HHG yield, we use different experimental schemes, including two-color pump, HHG using extended and multi-jet laser-produced plasmas, ablation of rotating target and temporal variation between the heating and driving pulses. A fivefold increase of harmonic yield from Al NP-containing plasmas compared to the plasmas containing only Al atoms and ions is obtained. The harmonics up to the 35th order are generated from the Al NP-containing plasmas. HHG calculations show that this cutoff is attributed to Al neutral atoms rather than Al ions. To interpret the experimental results, we also study the fundamental mechanism of NP formation. The simulations are carried out for different Al NP-containing ablation plumes. Our calculations and plasma debris analysis show the presence of NPs in the plasmas exposed to the driving 35 fs pulses.

Tracking the space debris from the Changchun Observatory

Changchun Observatory tracked Space Debris since Feb. 2014. This paper presents the technologies and results of Changchun station for space debris laser ranging (DLR) system. The system operates with a laser of 60 mJ/10 ns/500 Hz@532 nm laser and an optical camera for closed-loop tracking. Target selection assistant was introduced to DLR system. To represent the probability of return, the rebound index was calculated. Data identification was implemented in tracking control software and data processing. To improve the return rate, Range Bias/Time Bias is auto-corrected in the tracking software. The aim of this paper is to show the results and the analysis of the space debris observed during the period from the year 2014 to the year 2016. There are 491 passes observed for 232 different space debris targets were obtained during 35 terminator sessions. The observed targets are ranging between 460 km to 1800 km, with Radar Cross Sections (RCS) from $>15~\mbox{m}^{2}$ to $<1.0~\mbox{m}^{2}$ . The Root Mean Square (RMS) value of the range is measured to be less than 1 m for small targets, due to the 10 ns laser pulse length while for large objects it can reach up to 3.5 meters.

CFD analysis of suspended debris during postulated severe core damage accident of PHWR

A steady state CFD analyses for suspended debris with two different configurations are carried out for heat transfer assessment. Very low frequency postulated accident without mitigation can lead to fuel channels exposure for Pressurized Heavy Water Reactor (PHWR). The exposed fuel channels constitute suspended debris. The debris configuration changes from regular to a disassembled configuration with accident progression. Each fuel channel consists of nineteen pin bundles, sagged Pressure Tube (PT) and Calandria Tube (CT). The study shows an asymmetric heat distribution from fuel bundle to surroundings for debris with disassembled channels. This is due to contact among the channels and among the components of an individual fuel channel. The asymmetric heat distribution leads to higher peak fuel pin, PT and CT temperatures as compared to debris with regular configuration. It also increases the circumferential temperature gradient in constituting components of a fuel channel. Radiative heat transfer from fuel channel surface constitutes the major heat transfer for both the debris configurations; the debris bed with disassembled channels radiates 71% of its total energy dissipation as compared to 65.3% for regular configuration. A good extent of convective heat transfer takes place for regular configuration as space among channels allows the steam flow to take place. The analyses shows that predicted temperatures of the debris bed is limited with convective and radiative cooling, thus a large scale of component oxidation is not anticipated. Radiation heat transfer is found to be the major mode of heat transfer. Hence, a numerical study of the effect of emissivity (0.3–0.8) variation on fuel channel heat up is also studied. The maximum temperature variation of 164.5 °C is observed at the bottom (0°) of CT with emissivity variation.

Review on numerical analysis of electromagnetic characteristics for ferromagnetic wear debris

Wear is the main influential reason for the reliability and service life of machinery and the inductive monitoring is the most research and application of online ferromagnetic debris detection for its unique characteristics. In the electromagnetic characteristics analysis of the wear debris, the numerical analysis method can directly solve the problem of electromagnetic field in the form of value, program instead of analytic form. Based on the current research on numerical analysis of electromagnetic characteristics for ferromagnetic debris, the solved problems of numerical analysis are analysed. The core and theoretical basis of numerical analysis of electromagnetic characteristics are studied and assumptions and boundary conditions are provided. Then the present problems and future development trend of the numerical analysis of electromagnetic characteristics for ferromagnetic wear debris are discussed.

Optimization of wear parameters of Mg-(5.6Ti+3Al)-2.5B4C composite

PurposeThe purpose of this study is to analyse and optimize the wear parameters of magnesium metal-metal composite. Materials with lesser weight attract both the researcher and industrialists, as it exhibits the performance improvement in the automotive and aerospace industries. The enrichment of mechanical and tribological properties of the existing magnesium focussed the development of new metal–metal composite.Design/methodology/approachMetal–metal composite with magnesium matrix was synthesized through the disintegrated melt deposition technique with the addition of titanium, aluminium and boron carbide particles. The wear performance of the composite was experimented with the dry sliding wear test by considering load, sliding velocity and sliding distance.FindingsThe wear rate of the composite is analysed statistically, and the significance of wear parameters on the wear performance of metal–metal composite is observed. The worn pin surface and the wear debris collected during the wear experiments were exposed to the microscopy analysis to seize the dominating wear mechanisms.Originality/valueThe wear performance of the developed magnesium composite was analysed and discussed in detail with the support of scientific evidence, i.e. worn surface and debris analysis express the wear mechanisms.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2019-0326/

Application of likelihood ratios and optimal decision thresholds in fire debris analysis based on a partial least squares discriminant analysis (PLS-DA) model

A set of 9000 computationally generated (in-silico) total ion spectra comprising samples containing ignitable liquids from ASTM E1618-14 classes mixed with pyrolyzed substrates (class IL) and samples containing a mixture of pyrolyzed substrates without ignitable liquid contribution (class SUB) was used to generate a partial least squares discriminant analysis (PLS-DA) model. The training data set was balanced in IL and SUB class composition and the IL class samples were composed of a uniform distribution of ignitable liquids from the ASTM E1618-14 defined classes. The number of components in the optimized PLS-DA model, 13, was determined by optimizing the area under the receiver operating characteristic curve (ROC AUC) as a function of the number of components. Ten cross validation folds had an average ROC AUC of 0.930 ± 0.006. The PLS-DA model was further challenged with a uniformly distributed and balanced IL/SUB validation set of 1000 computationally mixed total ion spectra, giving an ROC AUC 0f 0.93. The model which had been validated on computationally generated total ion spectra was tested on a set of “real” fire debris samples from large-scale burn tests that had been independently evaluated by an “informed analyst”. The results from this study demonstrate the application of a chemometric model to the forensic analysis of fire debris data and emphasize the connection between quantified strength of the evidence and categorical decisions based on a defined operational decision point on the ROC curve. The success of the PLS-DA model demonstrates the feasibility of applying chemometric methods to the analysis of fire debris as a means of introducing probabilistic statements of evidentiary value to the court.

Clinical outcomes after carbon-plate osteosynthesis in patients with distal radius fractures

BackgroundSurgical implant material has changed over time, from metal to stainless steel to titanium. In recent decades a new material, carbon-fibre-reinforced polyether ether ketone, has been introduced. The aim of this study was to assess the clinical and radiological feasibility and functional outcome after treatment of distal radius fractures with this new implant.MethodsInclusion criteria: AO type B distal radius fractures treated with 2.7 mm CF/PEEK plates at one Level 1 trauma centre between 2016 and 2017. Follow-up period 1 year, measurement of range of motion and radiographic assessment, histological analysis of debris only after plate removal.ResultsOut of 112 eligible patients, 10 (8.9%) patients were included. Mean operation time was 65 ± 10 min. Radiographic healing was confirmed by radiologists at 6 weeks follow-up. During one-year follow-up, no adverse events were reported and functionality and patients subjective satisfaction improved significantly (p < 0.05). Only one plate was removed, with no histological signs of inflammation or allergic reaction.ConclusionsThe 2.7 mm CF/PEEK plate osteosynthesis appears to be a reliable and safe implant for certain types of distal radius fracture. Assessment of fracture union is substantially more practical and functionality improved significantly over 1 year.

Investigating the influence of titanium on wear characteristics of P/M hot extruded alloy steels

Powder metallurgy (P/M) processes is one of the fastest growing manufacturing fields. P/M process has outspread its applications in almost all the engineering fields like aerospace, automotive, manufacturing industries. P/M steels are most promising candidate materials for producing small components with high strength, but their wear resistances characteristics are mainly influenced by its alloy composition as well as the sintering conditions. The present work investigates the dry sliding wear characteristics of P/M hot extruded alloy steels with the addition of Titanium (Ti) in the Fe-1W-1C (base alloy). As these elemental alloy compositions find in numerous of applications as cutters, tools, bearing roller, fasteners, etc. The pin-on-disc tribometer was used to explore the wear characteristics at 2 m s−1 (constant speed) for a distance of 3600 m in ambient temperature. The extruded steel pins with a diameter of 6 mm were used for wear test against EN 38 steel disc as per ASTM G99 standard at 30, 50 and 70 N loads. The as-sintered microstructure exhibits the ferritic-pearlite structure. Alongside the microstructures of hot extruded alloy steels reveals the alternate lamellas as well as Widmanstatten ferrite, pearlite and bainite. The study assimilated that the addition of Titanium (4%) exhibited greater wear resistance due to the WTiC (secondary phase) embedded in the matrix of the Fe-W-C. The wear debris has been characterized by x-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The wear debris analysis confirms the presence of WTiC, TiC and the iron oxides in major amounts and small traces of Fe, WC. The delamination wear was observed as the common wear mechanism during lower loads, whereas the oxidative wear was predominant at higher loads.

Detection of Broken Impeller in Submersible Pump by Estimation of Rotational Frequency from Motor Current Signal

With the growth of automation in industry, it has become necessary to monitor the condition of machines and machinery systems to avoid sudden failures which may be catastrophic. There are various condition monitoring techniques available such as wear debris analysis, thermography, vibration analysis, motor current signature analysis (MCSA), etc. for fault detection of machines. Among these, MCSA is a new and emerging technique for fault detection of a submersible pump and other machineries. Apart from proper signal selection, the proper signal processing technique is also important for machinery fault diagnosis. A number of signal processing techniques such as FFT, STFT, and CWT are used for detection of faults by various researchers. In presence of fault, the speed of rotor changes. That will be hidden in the current signal in the form of modulation. Hence, instantaneous frequency (IF) estimation technique is an important technique, which can extract the hidden information. The present work attempts to detect the broken impeller in submersible pump using MCSA. Zero-crossing technique and frequency-domain-based IF estimation technique has been adopted to estimate IF from motor current signal and that has been used to detect the fault in submersible pump. Using these techniques, it is observed that the speed fluctuation increases when there is a defect or level of defect increases in impeller.

Analysis of oxide wear debris using ferrography image segmentation

PurposeIt is a challenging task to analysis oxide wear particles when they are stuck together with other types of wear particles in complex ferrography images. Hence, this paper aims to propose a method of ferrography image segmentation to analysis oxide wear debris in complex ferrography images.Design/methodology/approachFirst, ferrography images are segmented with watershed transform. Then, two region merging rules are proposed to improve the initial segmentation results. Finally, the features of each particle are extracted to detect and assess the oxide wear particles.FindingsThe results show that the proposed method outperforms other methods of ferrography image segmentation, and the overlapping wear particles in complex ferrography images can be well separated. Moreover, the features of each separated wear particles can be easily extracted to analysis the oxide wear particles.Practical implicationsThe proposed method provides a useful approach for the automatic detection and assessment of oxide wear particles in complex ferrography images.Originality/valueThe colours, edges and position information of wear debris are considered in the proposed method to improve the segmentation result. Moreover, the proposed method can not only detect oxide wear particles in ferrography images but also evaluate oxide wear severity in ferrography images.

Case study on the effectiveness of condition monitoring techniques for fault diagnosis of pumps in thermal power plant

Abstract A case study was carried out to investigate the effectiveness of condition monitoring techniques in the early failure detection of pumps in a thermal power plant. Various condition monitoring techniques used in this case study involved vibration analysis, motor current signature analysis, noise monitoring and wear debris analysis. These techniques were applied on the three pumps, namely boiler feed water pump, auxiliary cooling water pump and condensate extraction pump, which have to work continuously for the operation of the thermal power plant. Vibration analysis of the auxiliary cooling water pump showed that there is a rising trend in the acceleration values at its driving and non-driving end indicating the deterioration of bearings. Motor current index range of all the pumps was found to be within acceptable limits. Wear debris analysis of lubricant in the hydraulic coupling of boiler feed water pump indicated the presence of sand, dirt and low alloy steel sliding wear particles in it. Condition monitoring techniques have been proved to be an effective technique in early failure detection of pumps.

Nd isotopic structure of the Pacific Ocean 40–10 Ma, and evidence for the reorganization of deep North Pacific Ocean circulation between 36 and 25 Ma

Early Paleogene neodymium (Nd) isotopic reconstructions of ocean circulation in the Pacific suggest a bipolar mode of overturning circulation characterized by convection of deep-water masses from 70 to at least 40 Ma. This mode is fundamentally different from the “sluggish, diffusive” mode that characterizes the modern North Pacific. Therefore, major reorganization of Pacific circulation must have occurred between 40 Ma and the modern. To investigate the potential timing of such a reorganization, we present new Nd isotope data from drill sites spanning 40 to 10 Ma. Here, we use Nd isotopic analyses to identify the sources of dissolved Nd to the Pacific in order to evaluate the application of the Nd proxy for ancient water mass composition. We combine analyses of fossil fish debris, sequentially leached oxide coatings and leach residues to further refine our understanding of Nd marine geochemical cycling and to contribute new constraints on the paleoceanographic history of the Pacific. Overall, these data support previous interpretations of the convection of deep water in the Pacific sector of the Southern Ocean and surface-ventilated North Pacific Deep Water formation from ∼70 to 40 Ma. The new Nd isotope data suggest a gradual transition between 36 and 25 Ma, a time period characterized by global cooling. This transition consists of a change from North Pacific Nd isotopic signatures controlled by convection and water mass mixing to values heavily influenced by overprinting from other sources of Nd to the deep Pacific. Such a transition is consistent with a change in overturning circulation from a “Paleogene mode” to a mode dominated by sluggish diffusive mixing. After 25 Ma the data indicate a significant contribution of radiogenic dissolved Nd to the deep waters of the North Pacific. The most likely source of radiogenic dissolved Nd would have been labile volcanic ash that altered the composition of the water mass as it slowly advected through the North Pacific. A slowing of overturning circulation in the North Pacific could have resulted in diminished poleward heat transport, increasing equator to pole thermal gradients and contributing to a cooling global climate.

A Distillation Approach to Phase Equilibrium Measurements of Multicomponent Fluid Mixtures.

By building on the Advanced Distillation Curve (ADC) approach to measuring the volatility of fuels and other fluid mixtures, the ADC with Reflux or ADCR technique was developed to address the difficulty of experimentally determining the vapor–liquid equilibrium of fluids containing many components. For fuels and other multicomponent mixtures, the ADCR collects data about the chemical compositions of both liquid and vapor phases across a range of temperatures, elucidating the two-phase region at constant pressure. Two simple mixtures were used to demonstrate the ADCR method: an n-decane/n-tetradecane binary and the Huber-Bruno surrogate, a ternary mixture designed to represent the volatility of an aviation turbine kerosene. These mixtures were chosen to test the method because they have been extensively studied and modeled in previous work. For both test fluids, the ADCR measurements of vapor–liquid equilibrium were in good agreement with model predictions. We conclude that the ADCR is a useful method for determining the T-P-x-y behavior of fluid mixtures with many components. The experimental approach presented may support the development of fuels, design of separations, and forensic sciences that use vapor analysis, especially arson fire debris analysis, by providing quantitative data with well-characterized uncertainty describing the relationships between the vapor and condensed phases of a fuel subjected to thermal weathering.

Rapid concentration and isotopic measurements of ultra-trace 235U fission products with comparison to an ORIGEN isotope depletion model

This article presents the application of an automated online separation–direct analysis method, RAPID (Rapid Analysis of Post-Irradiation Debris), for the simultaneous measurement of both radioactive and stable fission isotopes from an irradiated highly-enriched uranium target. Developed for the measurement of the concentration and isotopic composition of over 40 elements down to the femtogram level, the RAPID method possesses the sensitivity, stability, and precision required to achieve accurate, low-level analyses of elements of non-natural origin. The isotopic compositions and concentrations of key fission elements cesium, strontium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, and samarium have been measured repeatedly over a six-week period. The validity of these measurements was confirmed using ORIGEN (Oak Ridge Isotope GENeration), an isotope depletion and decay modeling software, to within 1–3%.

In-Situ Fretting Wear Analysis of Electrical Connectors for Real System Applications

The tribological behavior of electrical contacts, especially separable type electrical connectors at low contact loads, are considered. The reliability of these connectors has been a major concern due to the fretting phenomenon that can lead to an unacceptable increase in contact resistance. This study analyzes various aspects of the fretting mechanism from a tribological perspective where friction and wear are the primary cause of degradation in electrical components. With the use of precise tribological equipment (high data acquisition rate of 5000 Hz), the electrical contact resistance and coefficient of friction at the contact interface are measured. The measurements were made in-situ for a simulated fretting environment under various constant loading conditions. It was observed that low contact loads (1 N) and low fretting frequency (1 Hz) leads to a high degree of fluctuation in the coefficient of friction. However, for the same conditions, the lowest wear rate and electrical contact resistance were observed. The reason behind this could be due to the lack of continuous electrical contact and a high degree of fretting frequency under low contact loads, ultimately leading to extended periods of an open circuit. Experimental analysis indicates the existence of an optimum loading condition at which the fretting wear effect is at its minimum. Detailed analysis of post fretting surface roughness, coating wear, and wear debris is conducted, as well as transfer film formations to explain the mechanism of fretting observed.