SMILE soft X-ray Imager flight model CCD370 pre-flight device characterisation

Throughout the SMILE mission the satellite will be bombarded by radiation which gradually damages the focal plane devices and degrades their performance.In order to understand the changes of the CCD370s within the soft X-ray Imager,an initial characterisation of the devices has been carried out to give a baseline performance level.Three CCDs have been characterised,the two flight devices and the flight spa re.This has been carried out at the Open University in a bespo ke cleanroom measure ment facility.The results show that there is a cluster of bright pixels in the flight spa re which increases in size with tempe rature.However at the nominal ope rating tempe rature(-120℃) it is within the procure ment specifications.Overall,the devices meet the specifications when ope rating at -120℃ in 6 × 6 binned frame transfer science mode.The se rial charge transfer inefficiency degrades with temperature in full frame mode.However any charge losses are recovered when binning/frame transfer is implemented.

Characterisation of Meteorological Drought in Northern Nigeria Using Comparative Rainfall-Based Drought Metrics

Meteorological droughts occur when there is deficiency in rainfall;i.e. rainfall availability is below some acclaimed normal values. Hence, the greater challenge is to be able to obtain suitable methods for assessing drought occurrence, its onset or initiation and termination. Thus, an attempt was made in this paper to evaluate the performance of Standardised Precipitation Index (SPI) and Standardised Precipitation Anomaly Index (SPAI) to characterise drought in Northern Nigeria for purposes of comparison and eventual adoption of probable candidate index for the development of an Early Warning System. The findings indicated that despite the fact that the annual timescale may be long, it can be employed to obtain information on the temporal evolution of drought especially, regional behaviour. However, monthly timescale can be more appropriate if emphasis is on evaluating the effects of drought in situations relating to water supply, agriculture and groundwater abstractions. The SPAI can be employed for periodic rainfall time series though;it accentuates drought signatures and may not necessarily dampen high fluctuations due to implications of high climatic variability considering the stochastic nature and state transition of drought phenomena. On the other hand, the temporal evolution of SPI and SPAI were not coherent at different temporal accumulations with differences in fluctuations. However, despite the differences between the SPI and SPAI, generally at some timescales, for instance, 6-month accumulation, both spatial and temporal distributions of drought characteristics were seemingly consistent. In view of the observed shortcomings of both indices, especially the SPI, the Standardised Nonstationary Precipitation Index (SnsPI) should be looked into and too, other indexes that take into consideration the implications of global warming by incorporating potential evapotranspiration may be deemed more suitable for drought studies in Northern Nigeria.

Overhanging rock slope by design:An integrated approach using rock mass strength characterisation,large-scale numerical modelling and limit equilibrium methods

Overhanging rock slopes(steeper than 90°) are typically avoided in rock engineering design, particularly where the scale of the slope exceeds the scale of fracturing present in the rock mass. This paper highlights an integrated approach of designing overhanging rock slopes where the relative dimensions of the slope exceed the scale of fracturing and the rock mass failure needs to be considered rather than kinematic release of individual blocks. The key to the method is a simplified limit equilibrium(LE) tool that was used for the support design and analysis of a multi-faceted overhanging rock slope. The overhanging slopes required complex geometries with constantly changing orientations. The overhanging rock varied in height from 30 m to 66 m. Geomechanical modelling combined with discrete fracture network(DFN)representation of the rock mass was used to validate the rock mass strength assumptions and the failure mechanism assumed in the LE model. The advantage of the simplified LE method is that buttress and support design iterations(along with sensitivity analysis of design parameters) can be completed for various cross-sections along the proposed overhanging rock sections in an efficient manner, compared to the more time-intensive, sophisticated methods that were used for the initial validation. The method described presents the development of this design tool and assumptions made for a specific overhanging rock slope design. Other locations will have different geological conditions that can control the potential behaviour of rock slopes, however, the approach presented can be applied as a general guiding design principle for overhanging rock cut slope.

Removal of Cu(II), Pb(II) and Zn(II) Ions from Aqueous Solutions Using Selected Agricultural Wastes: Adsorption and Characterisation Studies

The feasibility of durian tree sawdust (DTS), coconut coir (CC) and oil palm empty fruit bunch (EFB) as low-cost biosorbents for the removal of Cu(II), Pb(II) and Zn(II) ions from aqueous solutions was investigated. The effects of solution pH and initial metal concentration on adsorption capacity were examined in batch experiments. The affinity and the adsorption capacity of DTS, CC and EFB were evaluated. The adsorption behaviour of Cu(II), Pb(II) and Zn(II) ions onto DTS, CC and EFB was described using Freundlich and Langmuir isotherm models. The separation factor (RL) analysis suggests that the removal of metal ions onto three agricultural wastes studied was favourable. The maximum adsorption capacities (Q) estimated from the Langmuir isotherm model for Cu(II), Pb(II) and Zn(II) were 18.42, 20.37 and 22.78 mg/g for DTS, 18.38, 37.04 and 24.39 mg/g for CC, and 26.95, 37.59 and 21.19 mg/g for EFB, respectively. The characterisation studies were carried out using Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectrometer (EDX) and Fourier Transform Infrared Spectrometer (FTIR). The surface morphology of the biosorbents changed significantly following interaction with metal ions. The primary adsorption mechanism was complexation between metal ions and binding sites of biosorbents. Both hydroxyl and amine groups are the main binding sites in DTS, CC and EFB.

Biosorption of Cu(II), Pb(II) and Zn(II) Ions from Aqueous Solutions Using Selected Waste Materials: Adsorption and Characterisation Studies

The efficacy of coconut tree sawdust (CTS), eggshell (ES) and sugarcane bagasse (SB) as alternative low-cost biosorbents for the removal of Cu(II), Pb(II) and Zn(II) ions from aqueous solutions was investigated. Batch adsorption studies were carried out to evaluate the effects of solution pH and initial metal concentration on adsorption capacity. The optimum biosorption condition was found at pH 6.0, 0.1 g biomass dosage and at 90 min equilibrium time. The adsorption data were fitted to the Freundlich and Langmuir isotherm models. The adsorption capacity and affinity of CTS, ES and SB were evaluated. The Freundlich constant (n) and separation factor (RL) values suggest that the metal ions were favourably adsorbed onto biosorbents. The maximum adsorption capacities (Q) estimated from the Langmuir isotherm model for Cu(II), Pb(II) and Zn(II) were 3.89, 25.00 and 23.81 mg/g for CTS, 34.48, 90.90 and 35.71 mg/g for ES, and 3.65, 21.28 and 40.00 mg/g for SB, respectively. The characterisation studies were performed using Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectrometer (EDX) and Fourier Transform Infrared Spectrometer (FTIR). Interaction with metal ions led to the formation of discrete aggregates on the biosorbents surface. The metal ions bound to the active sites of the biosorbents through either electrostatic attraction or complexation mechanism.

Core-log integration and application of machine learning technique for better reservoir characterisation of Eocene carbonates,Indian offshore

Rock types,pore structures and permeability are essential petrophysical outputs,and they contribute considerably to the highest degree of uncertainty in reservoir characterisation.These factors have a strong influence on exploration and field development decisions.Core analysis is the best approach for estimating permeability,assigning rock types and characterising pore networks.Wireline logs are the most often employed method for estimating the parameters at each data point of reservoirs since there are more un-cored wells than cored wells.Artificial intelligence,on the other hand,is gaining popularity in the geosciences due to the ever-increasing complexity and volume of available subsurface data.This is also obvious in the demand for faster and more accurate interpretations in order to identify reservoir characteristics in increasingly difficult and complicated petroliferous basins.Artificial Neural Networks and Self-Organizing Maps are examples of machine learning approaches that can be used in both supervised and unsupervised modes for modelling and prediction.Eocene carbonates of Mukta oilfield are the major pay rocks of strong geological heterogeneity in terms of their porosity and permeability relationship with pore structures.This paper outlines a novel method of rock fabric classification,pore structure characterization,flow unit classification and robust reservoir permeability modelling based on an integrated approach that incorporates core measurements,log data and machine learning techniques.The pore structure has been characterised by the combination of conventional core,capillary pressure and nuclear magnetic resonance data.Artificial neural network has added an adequate benefit in accurate permeability modelling by utilizing the concepts of rock classifications and hydraulic flow units.

An experimental and numerical approach-characterisation of power cartridge for water-jet application

Power Cartridges are pyrotechnic devices where hot combustion gases utilized to do mechanical work for disruption of suspected Improvised Explosive Devices(IEDs). It plays a vital role either in destroying the suspicious object or making them non-functional by generating the gas pressure on burning of propellant against the water column inside the barrel, Present work is focused on characterisation,numerical solution such as deformation; strain; stress using FEM(Finite Element Method), design qualification, performance and evaluation of power cartridge for disruptor application. Experimental trials for pressure-time(P-t) measurement in closed vessel(CV), various electrical parameters like all fire current(AFC), no fire current(NFC) and ignition delay have been measured. Further, mechanical properties for brass material have been determined. An attempt has been made to characterise the power cartridge by FEM and carrying out the experiments for water-jet application.

Mechanical Characterisation of Densified Hardwood with Regard to Structural Applications

The demand for high-performance,yet eco-friendly materials is increasing on all scales from small applications in the car industry,instrument or furniture manufacturing to greater dimensions like floorings,balcony furnishings and even construction.Wood offers a good choice on all of these scales and can be modified and improved in many different ways.In this study,two common European hardwood species,Beech(Fagus sylvatica L.)and Ash(Fraxinus excelsior L.)were densified in radial direction by thermo-mechanical treatment and the densified product was investigated in an extensive characterisation series to determine all relevant mechanical properties.Compression in the three main directions(longitudinal,tangential,radial)and tension perpendicular to the grain(tangential,radial)were tested and compared to reference specimens with native density.Strength and modulus of elasticity were determined in all tests.In addition,a Life Cycle Assessment was carried out to evaluate the environmental impact associated to the densification process.The experimental investigations showed that strength and stiffness of hardwood in the longitudinal and tangential directions improve significantly by radial densification,whereas some properties in the radial direction decrease.The Life Cycle Assessment showed that artificial wood drying has higher impact than wood densification.Furthermore,the transport distance of the raw material highly influences the environmental impact of the final densified product.The paper then also offers an overview of possible applications in structural timber construction.Densified hardwood is a viable option as local reinforcement,where high compressive or tensile strength is needed.The wood densification process offers an alternative to the use of carbon-intense steel components or hardwoods from tropical forests.

Advanced Catalytic Membrane Characterisation and Gas Permeation Properties for Enhanced Ethyl Lactate Conversion

In this work, membrane evaluation, gas permeation properties and characterisation have been presented. A silica composite membrane was prepared, characterized and used for the permeation tests with four carrier gases to determine the most suitable carrier gas for enhancing the analysis of esterification product with gas chromatograph. The carrier gases used for the permeation tests were carbon dioxide (CO2), argon (Ar), helium (He) and nitrogen (N2). The permeation analysis was carried out between the gauge pressure range of 0.10 - 1.00 bar and temperature of 60℃. The gas flow rate was found to increase with respect to gauge pressure. The order of the gas flow rate with respect to the gauge pressure was Ar > CO2 > He > N2. The surface morphology and elemental composition of the membrane were analysed using scanning electron microscopy coupled with energy dispersive analysis of x-ray (the Zeiss EVO LS10). The SEM results exhibited a defect-free surface while the EDAX results identified different elements on the spectra including titanium (Ti), silicon (Si) and oxygen (O). Liquid nitrogen adsorption method (Quantachrome 2013 model) was used for the surface area and pore size distribution analysis. The Brunauer-Emmette-Teller (BET) surface area results of the 5th and 6th dip-coated membranes were 1.497 and 0.253 m2/g respectively, while the Barrette-Joyner-Halender (BJH) curves gave a pore size of 4.184 and 4.180 nm respectively for the 5th and 6th dip-coated membranes indicating a mesoporous structure. The BET curve exhibited a type IV isotherm. The BJH curve of the 6th dip-coated membrane showed a significant reduction in flow rate after the modification process. The membrane recorded a permeance in the range of to . The permeance relationship with the inverse square root of the gas molecular weight showed a linear proportionality with the flow of carrier gases confirming Knudsen flow mechanism of gas transport.

The Fabrication and Characterisation of Low-k Cordierite-Based Glas s-Ceramics by Tape Casting

Cordierite is a promising low-k material in mi cr oelectronic and packaging industries. When it is co-fired with the metal for re alising the multilayer circuits, temperature should be low enough to prevent the melting and/or oxidising of the metal. However, this temperature is usually too low to sinter cordierite. Low melting point glass, therefore, is added to the s toichiometric cordierite to lower the sintering temperature through a liquid-si ntering process. In this research work, cordierite-based glass ceramics tapes were prepared by t ape casting from suspensions containing different solids loading and different m ean particle sizes. The optimal experimental conditions for obtaining homogenous green tapes were determined by varying the type and concentration of dispersant s and binders, the solids loading as well as the particle sizes of both cordieri te and glass. Scanning electron microscopy (SEM) and Hg porosimetry were used to characterise the green tapes. The results showed that high values of solids vol ume fractions and of the size ratio between the mean particle sizes of glass and cordierite powders favour the obtaining of homogeneous and high dense substrate s. The dielectric constant of the sintered bodies at 1 100 ℃ was around 5 and t he dissipation factor was about 0.01 at 1 MHz.

Deposition and Characterisation of Nitrogen-Doped Zinc Oxide Thin Films by MOCVD Using Zinc Acetate—Ammonium Acetate Precursor

The synthesis and comprehensive analysis of nitrogen-doped zinc oxide thin films grown from a compound precursor of zinc acetate and ammonium acetate has been reported. The precursor was processed in different ratios of the zinc acetate-ammonium acetate additives, and each combination was used to deposit a thin film using metalorganic chemical vapour deposition (MOCVD) method. The produced thin films were characterised using Rutherford backscattering (RBS) spectroscopy, uv-visible spectrometry, x-ray diffractometry, four point probe measurements and optical microscopy. The deposited thin films showed a fairly consistent zinc:oxygen:nitrogen ratio of 4.4:3.7:1, the film structures were quasicrystalline and the sheet resistivities were high, while other familiar characteristics like optical transmittance, bandgap, thermal stability, etc. were maintained in the grown films. Applications in device fabrication and active sensor devices were hence envisaged as the emergent potentials of the thin films.

THE SYNTHESIS AND CHARACTERISATION OFASYMMETRIC HYDROMETHYL BEDT-TTF

A new bisethyldithionetetrathiafulvalene (ET) derivative was synthesised. The cyclic voltammogram comparison of asymmetric hydromethyl bisethyldithionetetrathiafulvalene (HMET) and ET was made. The single crystal of charge transfer complex HMETI(X) was obtained and characterised. The conductivity of the single crystal was measured between room temperature and liquid nitrogen temperature. This single crystal is a semiconductor in the liquid nitrogen temperature range.

Synthesis and Characterisation of Colorants Derived from 1,4-Diamino Anthraquinone Polyamides

In this study, the polycondensation products of a diamine anthraquinone (1,4-diamino anthraquinone) and some aliphatic diacids with different methylene numbers were synthesised. Their UV-visible spectroscopy and thermal properties were then characterised. The synthesis was achieved by reacting equimolar solutions of the amine and the acid halides. The structure and thermal properties of the products were characterised. FT-IR Spectra of all the three products revealed the formation of amide due to the presence of strong bands at 1565 and 3390 cm?1 assignable to C=O stretching and N-H vibrations. Differential Scanning Calorimetry revealed high melting exotherms for the products. Thermogravimetry revealed moderate thermal stabilities for Poly NAM and Poly NAS and low thermal stability for Poly NAA which indicated 5.9%, 7.1% and 61.2% weight losses at 285℃, 285℃ and 374℃ for the three products respectively. The wavelengths of maximum absorbance for the dye samples are 601.5, 591 and 589 nm respectively with absorptivity coefficients (a1cm1% ) of 11640000, 11610000 and 11560000 respectively.

Bacteriological and Physico-Chemical Characterisation of Liquid Wastes: The Case of the University Hospital Centre (UHC) of Yaoundé-Cameroon

The untreated effluents generated by hospital activities contribute to the dissemination of pathogenic germs and multi-resistant bacteria, thus presenting a great potential danger for health and the environment. The objective of this study was to evaluate the microbiological and physico-chemical quality of the effluents of the Yaoundé University Hospital Centre and their impact on the environment. It was a prospective and analytical study on three sites where hospital effluents from the intensive care unit (Station A), the upstream of the wastewater treatment plant (Station B), and the gynaecology, surgery and hospitalisation departments (Station C) were sampled. Samples were collected in sterile glass bottles for bacteriological analyses and polyethylene bottles for physico-chemical analyses. The bacteriological parameters measured showed that the density of the bacterial species sought was very high at Station B with a predominance of the species Escherichia coli (57.36%). At Station A, total coliforms were very abundant (50.12%) and at Station C, the genus Pseudomonas was predominant (14.69%). Bacteria of the genus Streptococcus were represented by three species, namely: Streptococcus agalactiae, Streptococcus faecalis, and Streptococcus pneumoniae. The Pseudomonas genus was also represented by 3 species, namely Pseudomonas aeruginosa, Pseudomonas maltophilia and Pseudomonas putida. The physico-chemical parameters showed that apart from temperature and conductivity, which were in compliance with the standards, the other had values higher than these standards. This study shows that untreated hospital effluent contains most of the bacteria involved in community, nosocomial infections and would be a potential source of risk to the surrounding population.

Characterisation of Zinc Oxynitride Thin Films Prepared Using Zinc(II) Complex of Hexamethylenetetramine as the Precursor

A Zinc(II) complex of hexamethylenetetramine was prepared as a single source precursor and used to deposit zinc oxynitride thin films. The thin films were deposited on soda-lime glass substrates using the Metal Organic Chemical Vapour Deposition (MOCVD) technique at the deposition temperature of 370°C and 390°C, respectively. The Fourier Transform Infrared Spectroscopy (FTIR) was used to determine the functional groups in the precursor, with stretching frequency for O-H, N-H, and C-H observed. The deposited films were characterized using UV-Visible Spectroscopy, Scanning Electron Microscopy (SEM), Elemental diffraction X-ray (EDX), and X-ray Diffractometer (XRD). A direct bandgap of 3.15 eV and 3.18 eV was obtained from the film deposited at 370°C and 390°C, respectively, using the Envelope Method. In comparison, a bandgap of 3.19 eV and 3.21 eV was obtained using the absorption spectrum fitting (ASF) method. The SEM revealed that the film is homogeneous, dense, and compact, composed of cluster grains. The EDX confirmed the presence of Zinc, Nitrogen and Oxygen. The X-ray Diffraction indicated the polycrystalline nature of the film.

Nano-scale pore distribution characterisation of coal using small angle X-ray scattering

In the process of coal seam fracturing with liquid nitrogen(LN_(2)),the change of coal pore structure has an important influence on the efficiency of coalbed methane(CBM)extraction.The nano-scale pore size distribution(PSD)in coal particles before and after freezing with LN_(2) are experimentally studied in this work.Coal samples are collected from four coal mines,where coal and gas outburst accidents have occurred.Small angle X-ray scattering technology(SAXS)and scanning electron microscopy(SEM)are used to study the pore structure changes of coal samples quantitatively and qualitatively.It is found that the scattering intensity of coal samples increases after freezing.The PSD of all samples significantly changes in the range of 0.8–7 nm,showing new pore spaces in 0.8–4 nm and fewer pores in the 4–7 nm range.Both the pore fractal dimension and the radius of gyration of coal samples increase after freezing and are mainly affected by the changes in pores and the anisotropy of the coal matrix.Crack expansion and pore connections are observed in the surface structure of the coal sample using SEM.This study provides a better understanding of the nano-scale mechanism of coal seam fracturing with LN_(2) for the prevention of coal and gas outbursts.

Contribution to the Characterization of Laterites Developed on Granitic Rock in Mbanga (Littoral-Cameroon): Significance in the Sustainable Pavements Design

The materials studied were lateritic soils from Souza-Mbanga-Cameroon, with a view to their better use in road geotechnics. In order to achieve the set objective, the work was carried out in two phases, firstly in the field, to provide a morpho-structural description of the soil profiles, followed by a laboratory phase to analyse the samples collected in the field. The results of the physical characterisation of the soil samples show that, for average values, the water content is 9.87%, the percentage of fines 48%, the plasticity index 21.6%, the liquidity limit 50.91%, and the consistency index 1.97. These soils are classified as silty sands in the LCPC classification and as fine soils in the GTR classification. The average value of the maximum dry density is 1.81 g/cm3 and that of the water content at the modified Proctor optimum is 16.24%. The CBR index is between 1.8% and 17.8%, showing that these soils belong to classes S1, S2, S3, S4 and S5. Souza-Mbanga lateritic soils can be used in their natural state as subgrades.

Cuttlebone： Characterisation, Application and Development of Biomimetic Materials

Cuttlebone signifies a special class of ultra-lightweight cellular natural material possessing unique chemical, mechanical and structural properties, which have drawn considerable attention in the literature. The aim of this paper is to better understand the mechanical and biological roles of cuttlebone. First, the existing literature concerning the characterisation and potential applications inspired by this remarkable biomaterial is critiqued. Second, the finite element-based homogenisation method is used to verify that morphological variations within individual cuttlebone samples have minimal impact on the effective me- chanical properties. This finding agrees with existing literature, which suggests that cuttlebone strength is dictated by the cut- tlefish habitation depth. Subsequently, this homogenisation approach is further developed to characterise the effective me- chanical bulk modulus and biofluidic permeability that cuttlebone provides, thereby quanti lying its mechanical and transporting functionalities to inspire bionic design of structures and materials for more extensive applications. Finally, a brief rationale for the need to design a biomimetic material inspired by the cuttlebone microstructure is provided, based on the preceding inves- tigation.

Synchrotron Characterisation of Ultra-Fine Grain TiB_(2)/Al-Cu Composite Fabricated by Laser Powder Bed Fusion

Isotropy in microstructure and mechanical properties remains a challenge for laser powder bed fusion(LPBF)processed materials due to the epitaxial growth and rapid cooling in LPBF.In this study,a high-strength TiB_(2)/Al-Cu composite with random texture was successfully fabricated by laser powder bed fusion(LPBF)using pre-doped TiB_(2)/Al-Cu composite powder.A series of advanced characterisation techniques,including synchrotron X-ray tomography,correlative focussed ion beam-scanning electron microscopy(FIB-SEM),scanning transmission electron microscopy(STEM),and synchrotron in situ X-ray diffraction,were applied to investigate the defects and microstructure of the as-fabricated TiB_(2)/Al-Cu composite across multiple length scales.The study showed ultra-fine grains with an average grain size of about 0.86μm,and a random texture was formed in the as-fabricated condition due to rapid solidification and the TiB_(2)particles promoting heterogeneous nucleation.The yield strength and total elongation of the as-fabricated composite were 317 MPa and 10%,respectively.The contributions of fine grains,solid solutions,dislocations,particles,and Guinier-Preston(GP)zones were calculated.Failure was found to be initiated from the largest lack-of-fusion pore,as revealed by in situ synchrotron tomography during tensile loading.In situ synchrotron diffraction was used to characterise the lattice strain evolution during tensile loading,providing important data for the development of crystal-plasticity models.