Selective preparation of lithium carbonate from overhaul slag by high temperature sulfuric acid roasting - Water leaching.

An efficient recycling process is developed to recover valuable materials from overhaul slag and reduce its harm to the ecological environment. The high temperature sulfuric acid roasting - water leaching technology is innovatively proposed to prepare Li2CO3 from overhaul slag. Under roasting conditions, fluorine volatilizes into the flue gas with HF, lithium is transformed into NaLi(SO4), aluminum is firstly transformed into NaAl(SO4)2, and then decomposed into Al2O3, so as to selective extraction of lithium. Under the optimal roasting - leaching conditions, the leaching rate of lithium and aluminum are 95.6% and 0.9%, respectively. Then the processes of impurity removal, and settling lithium are carried out. The Li2CO3 with recovery rate of 72.6% and purity of 98.6% could be obtained under the best settling lithium conditions. Compared with the traditional process, this work has short flow, high controllability, remarkable technical, economic, and environmental benefits. This comprehensive recycling technology is suitable for overhaul slag, and has great practical application potential for the disposal of other hazardous wastes in electrolytic aluminum industry.

Non-Destructive Identification of Fibre Orientation in Multi-Ply Biaxial Laminates Using Contact Temperature Sensors.

Fibre orientation within composite structures dictates the material properties of the laminate once cured. The ability to accurately and automatically assess fibre orientation of composite parts is a significant enabler in the goal to optimise the established processes within aftermarket aerospace industries. Incorrect ply lay-up results in a structure with undesirable material properties and as such, has the potential to fail under safe working loads. Since it is necessary to assure structural integrity during re-manufacture and repair assessment, the paper demonstrates a novel method of readily and non-destructively determining fibre orientation throughout multi-ply Biaxial woven composite laminates using point temperature contact sensors and data analysis techniques. Once cured, only the outermost laminates are visible to assess orientation. The inspection method is conducted visually, with reference guides to allow for rapid adoption with minimum training, as well as harnessing established temperature sensors within the Maintenance Repair and Overhaul (MRO) environment. The system is amenable to integration within existing repair/re-manufacture processes without significant impact to process flow. The method is able to identify noisy samples with an accuracy, precision and recall of 0.9, and for synthetically created samples of double the cure ply thickness, a precision of 0.75, a recall of 0.7 and an accuracy of 0.87.

Composite Laminate Delamination Detection Using Transient Thermal Conduction Profiles and Machine Learning Based Data Analysis.

Delaminations within aerospace composites are of particular concern, presenting within composite laminate structures without visible surface indications. Transmission based thermography techniques using contact temperature sensors and surface mounted heat sources are able to detect reductions in thermal conductivity and in turn impact damage and large disbonds can be detected. However delaminations between Carbon Fibre Reinforced Polymer (CFRP) plies are not immediately discoverable using the technique. The use of transient thermal conduction profiles induced from zonal heating of a CFRP laminate to ascertain inter-laminate differences has been demonstrated and the paper builds on this method further by investigating the impact of inter laminate inclusions, in the form of delaminations, to the transient thermal conduction profile of multi-ply bi-axial CFRP laminates. Results demonstrate that as the distance between centre of the heat source and delamination increase, whilst maintaining the delamination within the heated area, the resultant transient thermal conduction profile is measurably different to that of a homogeneous region at the same distance. The method utilises a supervised Support Vector Classification (SVC) algorithm to detect delaminations using temperature data from either the edge of the defect or the centre during a 140 s ramped heating period to 80 °C. An F1 score in the classification of delaminations or no delamination at an overall accuracy of over 99% in both training and with test data separate from the training process has been achieved using data points effected by transient thermal conduction due to structural dissipation at 56.25 mm.

Defect Detection in Aerospace Sandwich Composite Panels Using Conductive Thermography and Contact Sensors.

Sandwich panels consisting of two Carbon Fibre Reinforced Polymer (CFRP) outer skins and an aluminium honeycomb core are a common structure of surfaces on commercial aircraft due to the beneficial strength-weight ratio. Mechanical defects such as a crushed honeycomb core, dis-bonds and delaminations in the outer skins and in the core occur routinely under normal use and are repaired during aerospace Maintenance, Repair and Overhaul (MRO) processes. Current practices rely heavily on manual inspection where it is possible minor defects are not identified prior to primary repair and are only addressed after initial repairs intensify the defects due to thermal expansion during high temperature curing. This paper reports on the development and characterisation of a technique based on conductive thermography implemented using an array of single point temperature sensors mounted on one surface of the panel and the concomitant induced thermal profile generated by a thermal stimulus on the opposing surface to identify such defects. Defects are classified by analysing the differential conduction of thermal energy profiles across the surface of the panel. Results indicate that crushed core and impact damage are detectable using a stepped temperature profile of 80 ∘C The method is amenable to integration within the existing drying cycle stage and reduces the costs of executing the overall process in terms of time-to-repair and manual effort.

[Versa HD Volume-modulated Accelerator High Voltage Circuit Fault Maintenance].

This paper introduces a fast repair methods of Versa HD volume-modulated accelerator's high voltage circuit fault:the key points test method. To identify five key points:①Enter maintenance mode to check for AFC deviation; ② The magnetron waveform MI and PFN waveform PFN V are detected on the maintenance terminal board; ③ Detect thyratron waveform; ④ Check the supply voltage of thyratron; ⑤ HT PSU 600 V DC test 600 V normal or not. The waveform or voltage is also measured to efficiently narrow the fault range to find out the cause of the fault, quickly remove the fault.

Airborne contaminants during controlled residential fires.

In this study, we characterize the area and personal air concentrations of combustion byproducts produced during controlled residential fires with furnishings common in 21st century single family structures. Area air measurements were collected from the structure during active fire and overhaul (post suppression) and on the fireground where personnel were operating without any respiratory protection. Personal air measurements were collected from firefighters assigned to fire attack, victim search, overhaul, outside ventilation, and command/pump operator positions. Two different fire attack tactics were conducted for the fires (6 interior and 6 transitional) and exposures were compared between the tactics. For each of the 12 fires, firefighters were paired up to conduct each job assignment, except for overhaul that was conducted by 4 firefighters. Sampled compounds included polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs, e.g., benzene), hydrogen cyanide (HCN), and particulate (area air sampling only). Median personal air concentrations for the attack and search firefighters were generally well above applicable short-term occupational exposure limits, with the exception of HCN measured from search firefighters. Area air concentrations of all measured compounds decreased after suppression. Personal air concentrations of total PAHs and benzene measured from some overhaul firefighters exceeded exposure limits. Median personal air concentrations of HCN (16,300 ppb) exceeded the exposure limit for outside vent firefighters, with maximum levels (72,900 ppb) higher than the immediately dangerous to life and health (IDLH) level. Median air concentrations on the fireground (including particle count) were above background levels and highest when collected downwind of the structure and when ground-level smoke was the heaviest. No statistically significant differences in personal air concentrations were found between the 2 attack tactics. The results underscore the importance of wearing self-contained breathing apparatus when conducting overhaul or outside ventilation activities. Firefighters should also try to establish command upwind of the structure fire, and if this cannot be done, respiratory protection should be considered.

Respiratory protection for firefighters--Evaluation of CBRN canisters for use during overhaul II: In mask analyte sampling with integrated dynamic breathing machine.

According to the National Fire Protection Association there were 487,500 structural fires in the U.S. in 2013. After visible flames are extinguished firefighters begin the overhaul stage where remaining hot spots are identified and further extinguished. During overhaul, a significant amount of potentially hazardous chemicals can remain in the ambient environment. Previous research suggests that the use of air purifying respirators fitted with chemical, biological, radiological, and nuclear (CBRN) canisters may reduce occupational exposure. This study used large scale burns of representative structural materials to perform side-by-side, filtering, and service-life evaluations of commercially available CBRN filters using two head forms fitted with full-face respirators and a dynamic breathing machine. Three types of CBRN canisters and one non-CBRN cartridge were challenged in repetitive post-fire environments. Tests were conducted with two different breathing volumes and rates for two sampling durations (0-15 min and 0-60 min). Fifty-five different chemicals were selected for evaluation and results indicate that 10 of the 55 chemicals were present in the post-fire overhaul ambient environment. Acetaldehyde and formaldehyde were found to be the only two chemicals detected post filter but were effectively filtered to below ACGIH TLVs. Counter to our prior published work using continuous flow filter evaluation, this study indicates that, regardless of brand, CBRN filters were effective at reducing concentrations of post-fire ambient chemicals to below occupational exposure limits. However, caution should be applied when using CBRN filters as the ambient formaldehyde level in the current study was 8.9 times lower than during the previous work.

Respiratory protection for firefighters--evaluation of CBRN canisters for use during overhaul.

In the United States, there are approximately 366,600 structural fires each year. After visible flames are extinguished, firefighters begin the overhaul stage of firefighting to smother remaining hot spots and initiate investigations. Typically during overhaul significant ambient concentrations of chemical contaminants remain. However, previous research suggests that the use of air purifying respirators (APR) fitted with chemical, biological, radiological, and nuclear (CBRN) canisters may reduce occupational respiratory exposures. This pilot study used large-scale prescribed burns of representative structural materials to perform simultaneous, side-by-side, filtering and service-life evaluations of commercially available CBRN filters. Three types of CBRN canisters and one cartridge were challenged in repetitive post live-fire overhaul exposure tests using a sampling manifold apparatus. At a flow rate of 80 L/min, nine tests were conducted in the breathing zone for three different exposure durations (0-15 min, 0-30 min, and 0-60 min). Fifty different chemicals were identified for evaluation and results indicate that 21 of the 50 chemicals tested were in the air of the overhaul environment. Respirable particles and formaldehyde were consistently present above the American Conference of Governmental Industrial Hygienists (ACGIH®) recommended exposure level (REL) and threshold limit ceiling value (TLVc), respectively. Each filter effectively reduced concentrations for respirable particulates below the maximum recommended level. Formaldehyde was reduced, but not consistently filtered below the TLVc. These results were consistent across all exposure durations. This study indicates that, regardless of brand, CBRN filters provide protection from the vast majority of particle and gas-phase contaminants. However, due to formaldehyde breakthrough, CBRN filters do not provide complete protection during firefighter overhaul.

Stent-Graft Relining by Combined Aortic Cuff with Double-D Technique for Type IIIb or V Endoleak after Endovascular Aneurysm Repair: A Case Report.

We report the case of a 83-year-old man with aneurysmal sac enlargement after endovascular aneurysm repair for an abdominal aortic aneurysm, despite no overt endoleak (EL) detected on imaging. Occult type II EL was suspected, and treatment was performed. However, the aneurysm continued to enlarge. Thus, we diagnose with type V EL as exclusion diagnosis. We combined an aortic cuff and stent-graft leg to cover the initially inserted stent graft, as a diagnostic treatment for unrefined type IIIb EL. Subsequently, the aneurysm diameter decreased. This technique and concept may be effective for type V EL, which may include another type occult EL.

Joint Optimization of Process Flow and Scheduling in Service-Oriented Manufacturing Systems.

Customer-oriented management of manufacturing systems is crucial in service-oriented production and product service systems. This paper develops the selection of dispatching rules in combination with alternative process flow designs and demand mix, for a maintenance, repair and overhaul center (MRO) of turbo shaft engines, both for complete engines and engine modules. After an initial systematic screening of priority dispatching rules, the design of experiments and discrete-event simulation allows a quantitative analysis of the better rules for the alternative process flows with internal and service metrics. Next, the design of experiments with analysis of variance and the Taguchi approach enables a search for the optimal combination of process flow and dispatching rules. The consideration of extra costs for overdue work orders into the costing breakdown provides a quantitative evaluation of the optimum range of load for the facility. This facilitates the discussion of the significant trade-offs of cost, service, and flexibility in the production system and the operational management alternatives for decision-making.

Versa HD Volume-modulated Accelerator High Voltage Circuit Fault Maintenance / 中国医疗器械杂志

This paper introduces a fast repair methods of Versa HD volume-modulated accelerator's high voltage circuit fault:the key points test method. To identify five key points:①Enter maintenance mode to check for AFC deviation; ② The magnetron waveform MI and PFN waveform PFN V are detected on the maintenance terminal board; ③ Detect thyratron waveform; ④ Check the supply voltage of thyratron; ⑤ HT PSU 600 V DC test 600 V normal or not. The waveform or voltage is also measured to efficiently narrow the fault range to find out the cause of the fault, quickly remove the fault.