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Structural health monitoring (SHM) of a composite structure is essential in maintaining the integrity of the structure. Over the years, various studies have reported on the use of conventional electrical sensors in analysing acoustic wave propagation for delamination detection. However, electrical sensors are associated with drawbacks such as high signal attenuation, are prone to electromagnetic interference (EMI) and are not suitable for harsh environments. Therefore, this paper reported on the use of fiber Bragg grating (FBG) sensors for delamination detection. Two composite structures with delamination sizes of 10 cm × 2 cm and 10 cm × 6 cm were fabricated. Two FBGs were bonded before and after the delamination. In addition, three trials of impacts were induced at the centre of the structure. Multiple signal parameters were obtained and analysed, which were the time delay, amplitude difference and velocity difference. The experimental results revealed that the time delay, amplitude and velocity analysis varied for both the delamination sizes with an average percentage of 42.36%, 97.09% and 42.39%, respectively. Therefore, it was confirmed that the increase in delamination size resulted in a longer time delay, higher signal amplitude attenuation and slower wave propagation.

Structural Health Monitoring of engineering structures has become an essential measure for the prevention of catastrophic failures. This study presented a feasibility study of Fiber Bragg Grating-based Fabry-Perot interferometer (FBG-FPI) sensor for damage detection on an aluminum plate, by acoustic Lamb wave technique. In the investigation, a rectangular damage slot was introduced to the plate, at 15 cm from the actuator. Two FBG-FPI sensors were surface-mounted on the aluminum plate for the detection. In the analysis, we observed an additional wave packet with attenuated amplitude and time delay in the time-domain signal for the defect plate. Similar features are observed in the time-frequency spectrograms and they are important signatures that can be used for detecting the defect. The findings show the applicability of FBG-FPI sensor for damage detection on a thin-walled metallic structure.

Gamma-ray Bursts (GRBs) are the most powerful transients in the Universe, over-shining for a few seconds all other $\gamma$-ray sky sources. Their emission is produced within narrowly collimated relativistic jets launched after the core-collapse of massive stars or the merger of compact binaries. THESEUS will open a new window for the use of GRBs as cosmological tools by securing a statistically significant sample of high-$z$ GRBs, as well as by providing a large number of GRBs at low-intermediate redshifts extending the current samples to low luminosities. The wide energy band and unprecedented sensitivity of the Soft X-ray Imager (SXI) and X-Gamma rays Imaging Spectrometer (XGIS) instruments provide us a new route to unveil the nature of the prompt emission. For the first time, a full characterisation of the prompt emission spectrum from 0.3 keV to 10 MeV with unprecedented large count statistics will be possible revealing the signatures of synchrotron emission. SXI spectra, extending down to 0.3 keV, will constrain the local metal absorption and, for the brightest events, the progenitors' ejecta composition. Investigation of the nature of the internal energy dissipation mechanisms will be obtained through the systematic study with XGIS of the sub-second variability unexplored so far over such a wide energy range. THESEUS will follow the spectral evolution of the prompt emission down to the soft X-ray band during the early steep decay and through the plateau phase with the unique ability of extending above 10 keV the spectral study of these early afterglow emission phases., Comment: Submitted to Experimental Astronomy

The use of FBG sensors in water level monitoring has shown great advantages over the use of conventional electrical sensors. However, much effort is still required to increase their sensitivity towards water level measurement with eliminated sensitivity towards temperature. Here, the FBG was bonded on a PVC polymer plastic cantilever beam and rubber diaphragm structure. The sensing mechanism was based on the differential FBG method. Variations of the water level from 0 to 100 cm obtained the sensitivity of 0.0639 nm/cm with the linearity of 98.06%. The poor linearity was mainly due to the manual fabrication errors. However, this uncertainty can be overcome through the polynomial regression fit in determining the water level measurement. The measured water level was closed to the actual water level at a tolerance of ±2 cm. For temperature effects, the sensitivity was inconspicuous, recorded at only 0.0003 nm/°C across the range of 10 °C to 60 °C.

Fibre Bragg grating (FBG) pressure sensor has shown great potential in replacing the conventional electrical pressure sensor due to its adaptability to the harsh environment. However, increasing its resolution for low-pressure measurement is still a challenge. In this work, the bonding of FBG to a rubber-based diaphragm pressure transducer was proposed. The proposed pressure transducer had enhanced the sensitivity to 117.7 pm/kPa across the range of 40 kPa, which corresponded to the pressure resolution of 0.008 kPa. Furthermore, the proposed pressure transducer possessed a reference FBG for temperature compensation, where the overall temperature effect was less than 1%. &nbsp

High sensitivity pressure transducer is always in demand in many industrial applications. In this paper, a highly sensitive temperature discriminated pressure transducer based on the use of natural rubber diaphragm and chirped fibre Bragg grating (CFBG) is proposed and demonstrated. The sensing mechanism is based on the measurement of bandwidth change and total reflection power. Results showed that the use of rubber diaphragm enhanced the sensitivity, which was experimentally obtained at -276.7 pm/kPa. Furthermore, the pressure transducer was temperature insensitive and cost-effective due to the simple demodulation technique.

Pasting of half the grating of an FBG sensor on a natural rubber diaphragm was used to sense the pressure measurement. The pressure-induced strain on half of the grating resulted in bandwidth broadening. From the pressure range of 0 kPa to 20 kPa, the pressure sensitivity at 15 dB bandwidth changed was obtained at 77.7 pm/kPa with 99.94% of linearity. Through total reflected power monitoring via photodetector, the pressure transducer retrieved a sensitivity of 0.1686 dB m/kPa and evaded a complex demodulation technique. As a result of the temperature-independent bandwidth change, the pressure transducer was totally temperature insensitive.

A novel half-bonded chirped fiber Bragg grating on a natural rubber diaphragm has been proposed to enhance the sensitivity and to compensate the temperature effects of a hydrostatic liquid-level sensor. This innovative fabrication method is resulted in the narrowing of the bandwidth with the hydrostatic pressure sensitivity recorded at −253 pm/kPa and water column sensitivity at −0.0253 nm/cm. The bandwidth modulation measurement was insensitive to temperature variations when compared with center wavelength modulation measurement. Furthermore, the proposed hydrostatic liquid-level sensor is compatible with a low-cost photodetector.

Production Enhancement (PE) opportunities in a 30 years-old Field D in Balingian province, offshore of Sarawak, Malaysia are dwindling. Behind casing opportunities (BCO) in relation to bypassed pay with good reservoir properties are either already perforated and produced or too costly and complex to be executed due to well issues. An in-house evaluation tool, Resolution Enhanced Modelling (REM), was developed by PETRONAS Petrophysics Department to evaluate and characterize thin beds or laminations. These Low-Resistivity-Low-Contrast (LRLC) sands are commonly bypassed as conventional logging tools cannot resolve their true parametric values and the apparent log responses across these zones appeared as shaly sand. By running REM across these intervals, the properties of the thin sands can be properly characterized, improving the net pay and economics of perforating and producing these reservoirs. In addition, a Rock Type (RT) based technique was used to evaluate some LRLC candidates in Field D. REM was run on LRLC sections in idle wells to evaluate their potential. To derisk and test the methodology, Well A3 with relatively more promising results was chosen as the first well to be perforated. Moreover, both strings of Well A3 were idle which makes it operationally easier to carry out the perforation job. From the initial analysis, the LRLC intervals in Well A3 could contribute to additional reserves of 0.3 MMstb with start rate of 300 bopd. The job required usage of barge assisted coiled tubing to pump cement and shut off existing high watercut zone and slickline to perforate through tubing. The actual job duration was prolonged from 30 days to 50 days due to monsoon season, driving the cost up to twice the planned amount. Post perforation, the initial oil rate was tested to be 500 bopd. After increasing the choke size, the well could flow at 800 bopd. Convinced by the success of Well A3, the same methodology was applied to Well C8 located at the north side of the field. Well C8 encountered operational difficulties such as lower than expected top of cement and perforation gun malfunction, resulting in only 54% of the proposed depth being perforated. Well C8 produced high gas, with initial well test rate of 10 bopd. Managing a brownfield where the easy oil is mostly exhausted can be challenging. Therefore, the team has to be more creative in unlocking the remaining oil and prolonging the life of a well. By using REM, the overlooked potentials hidden in LRLC sands can be accurately estimated, making the economics to perforate them more attractive to pursue.

To control and equalize the horizontal well drawdown, Autonomous Inflow Control Device (AICD) are planned to be installed along the homogenous reservoirs in five infill wells at B field, Sarawak offshore (Malaysia). The very low viscosity contrast between oil and water (0.6cp and 0.5cp) with 37API degree at B gives unfavorable mobility ratio and water flows with a higher velocity than the oil. This paper presents the interdisciplinary approach to completion design needs which evaluated the efficiency and performance between conventional completions compared with passive inflow control device (ICD), AICD namely Rate Control Production (RCP) and Fluidic Diode to qualify the representative technologies for use at B fields. The very purpose of this flow control device is the extension of well life due to deferment of water and/or gas production prior to water and/or gas breakthrough occurs. Flow performance tests are used to measure the performance of these various flow control devices at representative downhole conditions. The comparative analysis was primarily based on elapsed time comparisons for water/oil ratio (WOR), gas/oil ratio and water cut and sensitivity to historical drawdown, productivity index and production cumulative performance. To reduce formation damage and screen plugging effect in these horizontal section, appropriate fluid conditioning, fluid displacement, filter cake breaker system and compatibility between screen and the fluid in which the bottom hole assembly (BHA) will be deployed are discussed in this paper. The gas-water-control completion using AICD technology is predicted to provide significant benefit during the field development with incremental oil recovery around 10-40%, allowing well production with low water and gas production.

Oil production from the field begin with the first oil in January 2003. Unfortunately, the wells produced viscous emulsion which caused the production decline rapidly. Further analysis of the production data showed that the decline in production over a long period of time is very consistent with organic deposition at or near the perforation interval. Over the years, several analyses and production enhancement efforts including chemical and mechanical treatments have been attempted with minimal success. The damaging mechanism was determined to be caused by rare High Molecular Weight Organic Deposit (HMWOD) that have caused a significant pressure drop in the tubing, which consequently restrict oil production and tested to only disperse at above 90°C. It was suspected that the deposit was a naturally-occurring component of the crude oil itself, separating from the bulk of the crude as a consequence of the fluids movement towards the wellbore and the consequent drop in fluid pressure. An eco-friendly nano-fluid was developed and pilot treatment conducted in February 2014, which successfully rejuvenated the well back to production. Subsequent treatment was conducted in early 2018 on the same well and later replicated on another well as part of technology maturation process. This paper incorporates laboratory tests conducted to customize the nano-fluid, engineering approach on the treatment volume, simulation analysis on treatment schedules, treatment procedure as guidance for offshore personnel and actual field result of the treatments. Remedial treatment for near wellbore HMWOD using novel nano-fluid has successfully revived the wells back to production. Further development and replication would open-up bigger opportunities to unlock potential of wells with similar organic deposit issue throughout PETRONAS' operation.

When a well has been diagnosed with formation damage, the norm is for operators to propose reservoir stimulation via acid/solvent pumping. In Field T, located offshore Bintulu in Malaysia, mineralogy understanding is limited as cores available only represent a few reservoirs. For those reservoirs which do not possess representative cores, it is a risk to prescribe any chemical. Historically, acid and solvent stimulation do not hold a good track record in T field. Hence, it is essential seek other stimulation methods that do not involve the requirement for mineralogy. The UST (ultrasonic stimulation) technology operates on the concept of ultrasonic waves combined with low frequency waves breaking nearby damage up to 1000m into the reservoir. The resonator is conveyed by E-line, hence, possessing a smaller footprint as compared to mobilization of a pumping unit and chemical tanks. Platforms in Field T are small, hence, bringing a pumping package onboard will require hiring a barge due to limited deck space. Seemingly, operational risks are reduced as there is no need for manual chemical handling. The selling point of this technology is minimal well downtime as the stimulation can be performed on a live well, which further reduces possibility of damaging formation during stimulation due to secondary chemical reactions. UST was piloted on 2 wells in Field T: Well X and Y. Well X showed an initial 30% gain post stimulation. Well Y was showing signs of clogged gas lift valves. Post operation observed pressure communication between tubing and casing which suggests that UST successfully broke the wax that was clogging the gas lift valves. A takeback from this project would be to not only stimulate the target reservoir, but to also stimulate the tubing walls and gas lift valves if there are any suspected valve plugging in the well. This paper will describe the technology that was used to stimulate the well in an environmentally friendly, non-invasive method. For fields with limited mineralogy data and deck space, it is recommended to explore an alternative stimulation method, such as UST, on the wells.

A Lamb waves-based technique for damage detection is one of the promising diagnostic tools due to their ease of excitation and detection along with their ability to travel long distances. However, their dispersive and multi-modal nature causing complicated wave signals and data interpretation in the damage detection process. The finite element method was performed in this study to understand their behaviour when interacting with defects for a successful implementation of this technique in Structural Health Monitoring system. FEA analysis was implemented to simulate the propagation of Lamb waves in the healthy and defective aluminium plate. The sensors are placed based on the configuration of the pulse-echo and pitch-catch method. It is noticed that there is an additional wave packet for the detected signals for defective plate based on the pulse-echo method whereas there is a significant delay in signal arrival for the pitch-catch method. This simulation study shows a significant feature extraction for the interactions of Lamb waves with defects. It is helpful for a good understanding before applying this technique for a real implementation.

This paper presented an aluminium diaphragm-based FBG pressure sensor for pressure measurement of underwater pipeline. The proposed pressure sensor obtained a pressure sensitivity of 2.43 nm/MPa across the range of 0 MPa to 0.3 MPa with good linearity of 99.95 %. Furthermore, this pressure sensor has also equipped with temperature sensing FBG for temperature compensation.

Considering the oil prices hovering at low levels, opportunities to reduce the cost and enhance productivities becomes the new routine, to improve the net present value, and reduce operating cost. Field A is located offshore West Malaysia with production started in 1960's. Idle or uneconomic producing wells went through detailed study to identify and appraise possible behind casing opportunities prior to plug and abandon. The detailed assessment targeted to verify hydrocarbon-bearing sands, in reservoirs known to be fine to very fine and interbedded silts and clays layers. To identify the present behind casing hydrocarbon saturation, and assess reservoir depletion, advanced pulsed neutron capture surveillance is used in the low contrast reservoir. A combination of elastic and inelastic pulse neutron logging, supplemented with total organic carbon (TOC) was carried out. TOC, Sigma, and near to far detectors were used to ascertain the presence of hydrocarbon. Results were compared to the open-hole saturation to identify possible depletion, and differentiate it from annulus-trapped hydrocarbon. Completion was cemented and considered as a new casing. Two self-oriented perforation runs were carried out in each interval to ensure penetrating the two casings into the reservoir. Results coming from pulsed neutron capture indicated presence of HC in various reservoirs; these results were cross-confirmed by sigma and carbon/oxygen logging. TOC computed oil volume is compared to the CO yields computed oil volume, and Sigma derived saturation to identify water bearing zones. Fluid typing was carried out to confirm the fluid properties are not changed. Contradicting results were looked into and verified. Sigma derived saturation was found to be influenced by complex lithology patterns such as carbonate and coal streaks. False HC indications such as behind annulus trapped oil and gas were identified using combination of thermal and burst rations with far and deep late capture curves. Redistributed saturation lead to firming new opportunities that were not considered earlier. Identified prospects were later categorized, and further allocated between long and short strings to minimize depletion and maximize well potential. Tubing annulus is cemented to ensure zonal isolation and ensure well integrity, as a result, two runs of perforations were planned for each interval to increase depth of penetration and improve productivity. The use of all available data allowed to derisk planned perforations and add additional resources. The developed workflow enlightens the best practice to budgetary recomplete low producing offshore wells. The niche low cost data acquisition, and assessment maximized and ascertained reservoir potential and ensure all available opportunities are looked into without being misled by late well life completion, cementation problems accumulated over time. The followed workflow ensured booking the additional reserves and allowed bringing well back to life at low cost.

A natural rubber diaphragm bonded with a single FBG is demonstrated to measure the pressure and temperature simultaneously. Half of the grating is bonded to the rubber diaphragm while the other half is bonded to the aluminium sheet. Under varying pressure at constant temperature, the sensitivity is recorded at 0.1007 nm/kPa with coefficient of 6.49 × 10−5 kPa−1. The temperature sensitivities at constant pressure is recorded at 0.0797 nm/°C and 0.0326 nm/°C, respectively. The experimentally obtained different sensitivities of the sensor in matrix equation approach capable to interpret the Bragg wavelength shifts into pressure and temperature information simultaneously.

Pressure measurement with a good sensitivity has always been a concern in most of the engineering applications and biomedical field. In this paper, a multiplexed FBG bonded on an ultrathin aluminium sheet which act as a cantilever deflected due to a deformation from a natural rubber based diaphragm has been proposed and studied. By using two gratings inscribed on a single optical fibre which senses the positive and negative strain has enhanced the sensitivity of the pressure transducer recorded at 329.56 pm/kPa or corresponding to 10.7893 kPa−1 across the range of 0 to 10 kPa with a good linearity of 99.76%. Furthermore, the thermal cross-sensitivity is compensated.

Flow assurance has been a big focus of oil and gas operation in ensuring the delivery of the targeted production. A few fields located offshore Malaysia have been experiencing solid deposition inside tubing and stable micro-emulsion from early stage of their life. Oil production from Field W begin in January 2003, unfortunately the wells produced viscous stable emulsion which caused the production decline significantly. Multiple analyses and efforts, including chemical and mechanical treatments, conducted over the years with minimal success. The damaging mechanism was determined to be caused by rare organic deposit that have caused a significant pressure drop in the tubing, which consequently restrict oil production and tested to only disperse at above 90°C. It was suspected that the organic deposit was a naturally occurring component of the crude oil itself, separating from the bulk of the crude as a consequence of the fluids movement towards the wellbore and the consequent drop in fluid pressure. This paper focuses on the step-by-step workflow developed to identify the solid deposition, laboratory testing, treatments conducted and the result of different chemical treatments in Field W. The ultimate effort was by developing an advanced eco-friendly nano-fluid to remediate the rare issue of High Molecular Weight Organic Deposit (HMWOD) in the fields. The nano-fluid pilot treatment was conducted in 2014 and successfully rejuvenate the well with total of 20,000bbl incremental oil volume. Early 2018, subsequent treatments were conducted that contributed substantial improvement to the field production and at lower total treatment cost. This advanced chemical using nano-fluid technology concept is deemed feasible and will be further replicated in other fields. This paper is highly beneficial to Operators, Petroleum and Flow Assurance Engineers experiencing flow assurance issue on organic scale such as microcrystalline wax, high molecular weight wax and stable emulsion in the crude production. This paper also promotes the use of nano-fluid technology as part of the solution to flow assurance issue in Oil and Gas industry.

Many oil and gas fields have long been suffering from sand production due to either the absence or failure of primary well sand control. To avoid mobilizing costly work-over rig to pull out the tubing, operators have tried various thru-tubing remedial sand control. The well's condition such as sands accumulation and space constraints due to small inner diameter of tubing always make this remedial job challenging. It is not surprising that the results are not all satisfactory. Among the industry-recognized remedial sand control, Stand Alone Screen (SAS) is the simplest and the cheapest method. Many SAS have been installed but most were failed with screen erosion as the main failure mechanism. Flowing high velocity fluid with sands wears out the screen fast making it impossible for the sands to bridge and to create formation sand pack around the screen. Ceramic Sand Screen (CSS) technology which was recently introduced to the industry aims to address this erosion issue. Having more than ten times hardness of stainless steel, sintered silicon carbide ceramic material in CSS offers superior resistance to wear. The pilot was conducted by installing CSS in three (3) selected wells with sand production history. While waiting for acoustic sand monitoring installation, the wells were put on production with the same choke size and regular manual samplings were conducted to monitor the sand production. The acoustic sand monitoring campaign began in November 2017. Sands production was carefully monitored during the process to determine the final choke size at which the wells would continuously produce. In the middle of the campaign due to adverse weather conditions, all non-essential personnel had to be abruptly demobilised from the field leaving acoustic sensors hooked-up to the respective flow line. This gave opportunity to have unplanned extended sand monitoring window. Loss of Primary Containment (LOPCs) occurred in two CSS wells not long after that. In one the choke body was heavily eroded and the other well had a punched hole at the first elbow of the flowline. These incidents prompted full investigation to be conducted. This included pulling out the installed CSS and performed tear down analysis. Acoustic sand monitoring that just happened to be available in one of the wells proved to be critical in understanding the CSS failure. The paper presents briefly on the CSS pilot project, the chronology of events until the incident, sands production trend from the acoustic sand monitoring. Using all available information, the paper provides details analysis on CSS failure mechanism.

This chapter reviews recent work on natural fiber–reinforced polyester hybrid composites. The vibration behavior of jute/roselle fiber–reinforced unsaturated polyester hybrid composites was also studied. All composite specimens were fabricated with the hand lay-up method, but with different layering sizes and sequences. A total of 12 types of jute (J)–roselle (S) woven fiber–reinforced unsaturated polyester resin hybrid composites were prepared, namely JJ, JS, SJ, SS, JJJ, SSS, SSJ, SJS, JSS, SJJ, JJS, and JSJ. The natural frequencies and damping properties obtained from experimental and numerical analyses through ANSYS finite element software were compared. The results showed that the varying layering sizes and layering sequences on the hybrid composites produced a significant effect on the natural frequency and damping ratio. Nevertheless, a high percentage of error (>20) was produced by the three-layer composites based on the numerical analysis.

Cantilever FBG accelerometer for low frequency application is usually modelled by single-degree-of-freedom (SDOF) system which gives linear strain-curvature relationship along the beam, even when the curvature is not linear especially when the excitation frequency is greater than fundamental frequency. This inaccurate prediction can be overcome by modelling the cantilever beam using Euler-Bernoulli (EB) theorem which considers MDOF systems. Therefore, this paper presents: (a) the validation of analytical works using EB theorem for cantilever beam and its comparison with Timoshenko (T) theorem (rotational inertia and shear force are considered) obtained from finite element method and (b) initial analysis of strain developed on cantilever beam using EB theorem and SDOF model at low frequency range. Despite the fact that the work in (a) is inequitable comparison, yet it is valid for the case of slender beam structure at low frequency range in this study. The results show that the dynamic characteristic and vibration response of a simple cantilever beam structure is not significantly affected by both rotational inertia and shear force at low frequency excitation, thus proves that the EB theorem is valid to be used in representing cantilever FBG accelerometer. In the second work (b), the strain computed from the EB theorem gives significant discrepancy in terms of value and pattern compared to SDOF model.

The pipeline is used as a medium of transportation in global gas and oil industries, providing the most efficient, convenient and transportation method for natural gas and oil from downstream to upstream production of the economical mode of the power station, refineries, and domestic needs. However, the pipeline leakages become a major concern as their failure may contribute to operational and economic loss as well as environmental pollution. This paper proposed a system to detect pipe fault at different locations. Empirical Mode Decomposition (EMD) was applied for feature extraction using energy and kurtosis. The one-against-one (OAO) and one-against-all (OAA) multiclass SVM with radial basis function (RBF), polynomial and sigmoid kernel functions were implemented in order to classify the multiple fault locations from the extracted features. RBF kernel function recorded the highest classification accuracy for both OAO and OAA approaches with 97.77% and 96.29%, respectively, followed by slightly reduced accuracy for sigmoid whereas significantly low accuracy for the polynomial kernel. The outputs were further analysed to justify the performance of the classifiers. From all the cases, it was observed that OAO-SVM with RBF kernel performed the best for pipe fault diagnosis.

Vibration measurement technique is very important in structural integrity monitoring. Various fibre Bragg grating (FBG) based accelerometers have been developed for vibration measurement. However, most of the researchers focused on high frequency monitoring and only few reported works are based on low frequency measurement. Therefore, this paper presented a low frequency FBG accelerometer based on Polyphenylene Ether (PPE) thermoplastic cantilever beam. The proposed FBG accelerometer was attached to a shaker and vibration signals were given with variations in frequency and acceleration. As a result, the FBG accelerometer has a sensitivity of 110 pm/g and natural frequency of 9 Hz. The proposed accelerometer capable to detect low frequency of 2 Hz at 0.04 g which is suitable for utilisation in seismic monitoring of earthquake.

Abstract — The removal of mercury from entering process area is the key to safeguard aluminum brazed heat exchanger and other critical equipment in the ethylene production plant from Liquid Metal Embrittlement (LME) and amalgam corrosion. Sulphur Impregnated Activated Carbon (SIAC) is the proven technology for mercury removal. However, currently there is no specific study conducted at fluctuating ethane feedstock to monitor its functionality and performance. This study is conducted at a large scale of aging ethylene plant without Ethylene Buffer Storage Tank (EBST) which results in fluctuating feedstock upstream of mercury removal vessel. Number of experiments and data gathering were done by observing current mercury level at various process stream to determine its performance before and after installation. Analysis performed at mercury removal vessel's outlet indicates consistent decrease in adsorption capacity with an increase of temperature. The fluctuation of ethane feedstock from 35,000 kg/hr to 71,000 kg/hr also results in less adsorption efficiency of SIAC.

A diaphragm-based hydrostatic level transducer with the use of a single Fibre Bragg grating (FBG) is presented for simultaneous measurement of water level and temperature. In order to distinguish the mismatch between water level and temperature sensitivity, a bandwidth modulation and centre wavelength shift measurement technique was introduced. The change in bandwidth is sensitive towards water level variations with a sensitivity of 0.0015 nm/cm. Meanwhile, the change of centre wavelength is sensitive towards water level and temperature variations, with sensitivities of 0.0008 nm/cm and 0.0365 nm/°C, respectively. By expressing the obtained sensitivities in a matrix equation approach, simultaneous water level and temperature measurement can be predicted accurately.

Pressure sensors are the essential equipment in the field of pressure measurement. In this study, an aluminium diaphragm-based fibre Bragg grating (FBG) pressure transducer with temperature compensation strategy is presented. FBG-based sensors are good for certain applications, such as biomedical, combustion chamber and pressure vessel; particularly those involving harsh enviroment and high electromagnetic disturbance. One of the greatest challenges for utilising an FBG-sensor based transducer is the unstable output spectrum due to temperature variations. This phenomenon results in a huge variation in pressure readings, thus contributing to accuracy problem. To overcome the problem, this study introduced an approach to solve the inconsistency of sensor output by utilising two FBGs that were bonded at the centre of the diaphragm (FBG sensor) and at the base of the pressure transducer (FBG reference). The inconsistency of wavelength was eliminated by normalising the Bragg wavelength variation from the FBG sensor (∆ƛFBG1) with respect to Bragg wavelength variation from the FBG reference (∆ƛFBG2). The results indicated that the FBG pressure transducer had a sensitivity of 2.8485 nm/MPa at room temperature within the range of 22.9°C to 27.8°C and a linear fitting coefficient of 99.97% in a pressure that ranged from 0 MPa to 0.5 MPa. This FBG pressure transducer with temperature compensation technique was proven to be suitable for the pressure measurement of gas with an average error of 2.32% as compared to the conventional pressure gauge available in market.

Fibre Bragg grating (FBG) pressure sensors show a great potential in replacing conventional electrical pressure sensors due to their numerous advantages. However, increasing their pressure sensitivity performance for low hydrostatic pressure measurement is still a challenge. This paper reviewed recent pressure sensitivity enhancement methods that could be divided into two groups, namely intrinsic and extrinsic. For the intrinsic enhancement method, this paper reviewed polymer FBGs, special fibre sensors, interferometric sensors, and special grating sensors. For the extrinsic enhancement method, polymer-based pressure transducers, diaphragm-based pressure transducers, and other structure-based pressure transducers were reviewed in detail.

The burning rate is a crucial element in the performance of a solid propellant rocket. Strand burner is a device used to measure the propellant burning rate at elevated pressure. Solidworks Simulation is one of the software that is capable of performing finite element analysis that widely used to estimate the mechanical behavior of materials and structures in engineering applications. The objective of this paper is to analyze stresses in developing safe strand burner by using Solidworks Simulation. The strand burner is designed and analyzed using Solidworks 2016 software. Solid standard mesh meshing element is selected for purpose. The withstand loads and stresses on strand burner physically structure is measured by both simulation analysis and hand calculation. The result show the safety factor on developing strand burner is obtained by both method is 2.31. Based on safety factor generated, the strand burner can be test until 60.61 bars (6.061 MPa). In conclusion, the burning test inside the strand burner chamber can be test up to 126 bars. The design is safe for operating conditions.

THESEUS is a space mission concept aimed at exploiting Gamma-Ray Bursts for investigating the early Universe and at providing a substantial advancement of multi-messenger and time-domain astrophysics. These goals will be achieved through a unique combination of instruments allowing GRB and X-ray transient detection over a broad field of view (more than 1sr) with 0.5¿1 arcmin localization, an energy band extending from several MeV down to 0.3¿keV and high sensitivity to transient sources in the soft X-ray domain, as well as on-board prompt (few minutes) follow-up with a 0.7¿m class IR telescope with both imaging and spectroscopic capabilities. THESEUS will be perfectly suited for addressing the main open issues in cosmology such as, e.g., star formation rate and metallicity evolution of the inter-stellar and intra-galactic medium up to redshift 10, signatures of Pop III stars, sources and physics of re-ionization, and the faint end of the galaxy luminosity function. In addition, it will provide unprecedented capability to monitor the X-ray variable sky, thus detecting, localizing, and identifying the electromagnetic counterparts to sources of gravitational radiation, which may be routinely detected in the late ¿20s/early ¿30s by next generation facilities like aLIGO/ aVirgo, eLISA, KAGRA, and Einstein Telescope. THESEUS will also provide powerful synergies with the next generation of multi-wavelength observatories (e.g., LSST, ELT, SKA, CTA, ATHENA).© 2018 COSPAR, S.E. acknowledges the financial support from contracts ASI-INAF 1/009/10/0, NARO15 ASI-INAF 1/037/12/0 and ASI 2015-046-R.0. R.H. acknowledges GACR grant 13-33324S. S.V. research leading to these results has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no 606176. D.S. was supported by the Czech grant 1601116S GA CR. Maria Giovanna Dainotti acknowledges funding from the European Union through the Marie Curie Action FP7-PEOPLE-2013-IOF, under grant agreement No. 626267 (>Cosmological Candles>).

An integration of Structural Health Monitoring (SHM) into composite structures contribute towards the development of smart composites structure. Smart-structure offers an ability have a continuous and real-time information of its circumstances under critical loading applications. One of the main objectives in this research study was the development of the Fiber Bragg grating (FBG) sensor system for SHM of thin composite laminates. Not only that, this work has been utilizing the FBG sensors in the Near Infra-red (NIR) range; ∼830 nm, as an alternative to the applications of the conventional 1550 nm FBG sensors. The capability of this sensor system was validated with the impact location determination test on a thin composite plate. It showed a very promising result whereby the relative error falls below 10%.

The understanding of Lamb wave propagation and its interaction with defects are crucial part of SHM technology. Being of high relevance due to the costs of experimental equipment, the dynamic finite element analysis is performed in this study. FEA analysis was implemented to simulate propagation of Lamb waves in healthy and defective aluminium plate. The wavefield visualisation shows a high degree of difference between these two plates, which shows the interaction with defects. This study is useful for a good understanding of the Lamb wave interaction with defect before applying this method for a real application.