43 research outputs found
A Sophisticated Terahertz Photonic Crystal Fiber Sensor Design for Highly Accurate Detection of Kerosene Mixtures
No full textAbstract A Photonic Crystal Fiber sensor has been proposed, featuring an octagonal cladding and a hollow core, designed specifically for detecting kerosene adulteration. The sensor's performance is evaluated through numerical simulations across frequencies ranging from 1.0 to 3 THz. Kerosene is established into the innermost hole of the structure, and the strut size is adjusted to analyze the sensor's functionality at THz frequencies. At 2.2 THz, the sensor demonstrated impressive results, with a relative sensitivity of around 96.80%, an effective mode loss (EML) of 0.00667 cm−1, and a very low confinement loss of ≈6.78 × 10⁻8 dB m−1. This high sensitivity and precision make the proposed detector a promising tool for identifying kerosene adulteration, ensuring consumers receive high‐quality petroleum products. Additionally, modern techniques like extrusion and 3D printing can be employed to manufacture the photonic crystal fiber indicator
Emphasis on sensitivity and accuracy: Design and optimization of a high-sensitivity terahertz photonic crystal fiber sensor for precision analysis of petrochemical-based adulterants in hydrocarbon mixtures
No full textThis study introduces an innovative octagonal cladding with hollow-core photonic crystal fiber (PCF) sensor designed for the identification of kerosene adulteration within the terahertz (THz) spectral domain. The sensor's performance is rigorously assessed through simulations conducted using COMSOL Multiphysics, a high-fidelity platform based on the finite element method (FEM) for analyzing complex electromagnetic behaviors within the fiber structure. The sensor's performance was estimated throughout numerical simulations across frequencies varying from 1.0 to 3 THz. Simulation results demonstrate that the optimized design achieves an outstanding relative sensitivity of 97.20% at a target frequency of 2.2 THz, markedly surpassing the capabilities of existing sensing technologies. Moreover, the sensor exhibits extremely low confinement loss, measured at 6.08 × 10−8 dB/m, along with a minimal effective material loss of 0.00654 cm−1. These characteristics enable the precise detection of minute refractive index differences associated with the unique chemical profiles of various petroleum-based fuels. The high sensitivity and low-loss performance of the proposed sensor support non-invasive and non-destructive testing, ensuring that the samples remain unaltered during analysis. The exceptional sensitivity and accuracy of the proposed sensing system position it as a highly effective solution for detecting kerosene adulteration, thereby safeguarding the quality of petroleum-based fuels for end users. Furthermore, advanced fabrication methods such as extrusion and additive manufacturing may be utilized to produce the photonic crystal fiber-based sensor with enhanced structural precision and scalability
MFN Provisions and Related Issues in Bilateral Investment Treaties
No full textMFN provisions have been interpreted in a broad manner allowing the stakeholders to bring in financially beneficial provisions from other BITs. Using this broad interpretation, the policy instrument gives the opportunity to the investor to shop around for suitable provisions of BITs during disputes. The orthodox application provides substantive protection under the forum of international trade law, but in the field of international investment law this provision is used for both substantive and procedural treatment in the area of the investor-state dispute-settlement mechanism. What makes it more challenging is when the investor or the state invokes the investor-state dispute-settlement procedure before a different international settlement forum. Interestingly, the investor and the state earlier agreed on dispute-settlement forums via their BITs, but there are a lot of examples where a state has tried to receive protection from their domestic court in an international matter. Besides, MFN provisions are used for bypassing various requirements for establishing formal international arbitration. So, due to lacunae in government mechanisms, political instability and the lack of knowledge on the BIT’s binding nature, countries have to face legal and economic hurdles after signing it. In this article, the author has tried to discuss this broad interpretation of the MFN provisions of BITs by discussing existing cases of investor-state dispute settlement related to MFN provisions. The author has tried to focus on two basic subjects: a) MFN provisions and related issues regarding investment, and b) MFN provisions and jurisdiction
Design of a porous cored hexagonal photonic crystal fiber based optical sensor with high relative sensitivity for lower operating wavelength
No full textAbstract In this article, highly sensitive and low confinement loss enriching micro structured photonic crystal fiber (PCF) has been suggested as an optical sensor. The proposed PCF is porous cored hexagonal (P-HPCF) where cladding contains five layers with circular air holes and core vicinity is formed by two layered elliptical air holes. Two fundamental propagation characteristics such as the relative sensitivity and confinement loss of the proposed P-HPCF have been numerically scrutinized by the full vectorial finite element method (FEM) simulation procedure. The optimized values are modified with different geometrical parameters like diameters of circular or elliptical air holes, pitches of the core, and cladding region over a spacious assortment of wavelength from 0.8 µm to 1.8 µm. All pretending results exhibit that the relative sensitivity is enlarged according to decrement of wavelength of the transmission band (O+E+S+C+L+U). In addition, all useable liquids reveal the maximum sensitivity of 57.00%, 57.18%, and 57.27% for n=1.33, 1.354, and 1.366 respectively by lower band. Moreover, effective area, nonlinear coefficient, frequency, propagation constant, total electric energy, total magnetic energy, and wave number in free space of the proposed P-HPCF have been reported recently
Design of highly sensible porous shaped photonic crystal fiber with strong confinement field for optical sensing
No full textDesign of a novel photonic crystal fiber and numerical analysis of sensitivity for the detection of illegal drugs in terahertz regime
No full textIn this study, a novel photonic crystal fiber (PCF) based drug sensor has been introduced. The core and cladding area of the hexagonal fiber structure (H-PCF) has round air holes. We examined the model in the THz regime using the FEM and the COMSOL Multiphysics Software platform. With this updated model, the sensitivity to detect amphetamine (n = 1.518), cocaine (n = 1.5022), and ketamine (n = 1.562) at 1 THz is 89.50%, 90.20%, and 85.50% accordingly. Furthermore, the suggested fiber, operating at 1 THz, generated a vast effective area of Ketamine (n = 1.562), cocaine (n = 1.5022), and amphetamine (n = 1.518) of 1.37 × 10−7 m2, 1.40 × 10−7 m2, 1.39 × 10−7 m2 and relatively low confinement loss of 6.40 × 10−8 dB/m, 7.10 × 10−8 dB/m, 6.20 × 10−8 dB/m and negligible effective material loss of the structure of 0.02 cm−1. After all, we can say that abuse of drugs produces not only short-term effects but also long-term, catastrophic consequences for human health, including the potential for death. Therefore, it is essential to identify illegal drugs with high efficiency and precision. So, this H-PCF structure that we have proposed will be ideal for illegal drug detection
MFN Provisions in Bilateral Investment Treaties of South Asian Countries: An Analysis
No full textA number of Bilateral Investment Treaties have been signed with South Asian countries (BITs). MFN clauses were added in these treaties, and they were construed extremely broadly, allowing investors to borrow favorable dispute settlement measures from third-country BITs. When disagreements emerge, this dynamic policy tool allows investors to cherry select more favorable treatment from third-party BITs under the cover of wide interpretation. In the sphere of international trade law, where the traditional use of MFN attempted to provide substantive protection, this provision is applied in the domain of investor-state dispute settlement mechanisms for both substantive and procedural treatment. Furthermore, the MFN clause is utilized to get around a number of prerequisites for establishing official international arbitration. For this, MFN provision is widely used to get a quick remedy with ambiguous interpretations. The author, in this article, will try to indicate the area of the problem of using the MFN provisions in the context of shortening the waiting period, widening the jurisdictions etc.LLMMSc/M
A Novel Hexahedron Photonic Crystal Fiber in Terahertz Propagation: Design and Analysis
No full textA novel hexahedron fiber has been proposed for biomedical imaging applications and efficient guiding of terahertz radiation. A finite element method (FEM) has been applied to investigate the guiding properties rigorously. All numerically computational investigated results for optimum parameters have revealed the high numerical aperture (NA) of 0.52, high core power fraction of 64%, near zero flattened dispersion of 0.5 ± 0.6 ps/THz/cm over the 0.8–1.4 THz band and low losses with 80% of the bulk absorption material loss. In addition, the V–parameter is also inspected for checking the proposed fiber modality. The proposed single-mode hexahedron photonic crystal fiber (PCF) can be highly applicable for convenient broadband transmission and numerous applications in THz technology
Advanced THz Optical Sensor for Ethanol and Benzene Detection: A Step towards Safer Industrial and Environmental Monitoring
No full textEthanol and Benzene are harmful to climate change, the human body, biodiversity, and long-term ecosystem balance. Normally, ethanol is added to gasoline, which causes climate change, and benzene is used in industries, which can cause cancer. Therefore, it is crucial to accurately identify both ethanol and benzene to ensure people's safety in the environment. This study shows a new and powerful photonic crystal fiber (PCF) sensor that uses terahertz (THz) technology. This sensor is designed to detect ethanol and benzene with high accuracy. The sensor works better because it has a special shape with a six-sided (hexahedron) center and a hexagonal outer cladding layer. According to our experiments, at 2.2 THz, the PCF sensor achieves relative sensitivities of 96.35 % for ethanol and 97.05 % for benzene. Effective Material Loss (EML), Effective Area, and Confinement Loss (CL) for ethanol and benzene are 0.0032 cm−1 and 0.0024 cm−1, 6.88 × 10−8 m2 and 7.79 × 10−8 m2 respectively, and 1.84 × 10−7 dB/m and 1.89 × 10−7 dB/m respectively, with operating frequency at 2.2 THz. There are various traditional detection techniques to detect those chemicals, but this proposed optical sensor performs better. So, the proposed PCF sensor demonstrates high sensitivity in simulation and indicates promising potential for future application in industrial safety and environmental monitoring
Do the features of urban green spaces that promote social and active ageing vary by international context? Comparison between and within Sydney, Dhaka and Singapore
No full textBackground: The challenges of demographic and epidemiological transition around the world have created the need for ageing-friendly cities. Urban green spaces (UGS) are considered to be an important health and wellbeing resource, the role of which can be expanded to include the promotion of social and active ageing. There is accumulating evidence on the positive association between the quantity and quality of UGS and reduced risk of different types of noncommunicable and chronic diseases (NCDs) often associated with ageing. UGS is found to be associated with reduced risk of NCDs through multiple pathways including engaging in physical activities (PA) and increased social interaction. There is also evidence, as yet inconsistent, on the moderating effect of socioeconomic circumstances on these associations. A problem in the available evidence is that more than 90% of the evidence is geographically skewed to high-income and western countries (HICs). In addition, very few studies so far conducted have particularly focused on the role of UGS on the outdoor recreation activities of the ageing population. Therefore, this PhD study explores the extent to which inequitable distribution and quality of neighbourhood green spaces are associated with the level of outdoor recreational activities in multiple and geodemographically diverse cities. Methods: The research design is principally based on five interrelated research questions which start with a systematic scoping review on the current evidence from the low and middleincome countries on the UGS and health research. To answer the subsequent research questions, both primary and secondary observational data collection was undertaken in a highincome, ‘Western’ city (Sydney, Australia), a high-income Asian city (Singapore) and a low and the middle-income city (Dhaka, Bangladesh). The study used a geographic information system (GIS) based UGS data and observation auditing tool to measure UGS quantity and quality respectively. The quantity of UGS was measured by calculating fixed boundary-based UGS availability and flexible boundary-based UGS accessibility. UGS quality data were collected by using an adapted version of the CPAT (Community Park Auditing Tool). The author also collected data on different types of use of UGS by people using a systematic observation tool adapted from SOPARC (System for Observing Play and Recreation in Communities). The socioeconomic circumstances together with the share of the ageing population (defined as aged 60 and above in Sydney and Singapore and as aged 50 and above in Dhaka) measured at the neighbourhood scale were used as potential moderators to analyse the inequity of UGS quantity and quality. Depending on the nature of outcome variables, multiple regression and Poisson regression modelling techniques were used at different stages of the research. Results: The 22 studies were found from 11 LMICs through the systematic scoping review following PRISMA guidelines. Compared to the existing evidence-based in HICs, this review found fewer types and numbers of health aspects to relate to UGS exposures. While heterogeneous results were previously reported in the HIC based studies, the association was consistently positive with mental health, wellbeing and self-reported health aspects in the LMIC contexts except in one study. The similarity was found with HIC in regards to the reported association between UGS and physical health. To understand whether UGS is evenly distributed across the case cities, the investigation of UGS quantity (measured by availability and accessibility) in this research found an inconsistent pattern of the socioeconomic inequity in the three case cities. Socioeconomic circumstances were found to have a strong positive association with the UGS availability in Sydney, whereas the association was significantly negative in Dhaka. In Singapore, this association was positive but statistically not significant. The percentage of the ageing population within a neighbourhood appeared to be independently associated with higher amount of UGS in Sydney and lower amount in Singapore. In these cities, the proportion of the ageing population is already higher than Dhaka. Accessibility measures were not associated with the socioeconomic circumstances except in Dhaka, where a strong negative association between socioeconomic circumstances and accessibility index was observed. The percentage of the ageing population showed a significant non-linear association with PWD only in Singapore. The population density was found to be an important predictor of UGS distribution in all the three cities. The population density was negatively associated with the UGS availability and accessibility in the medium density neighbourhoods of Sydney. While high accessibility was positively associated with high density in Singapore, it was negatively associated in Dhaka. After scoring the UGS quality within a standard scale and classifying the quality of sample UGS into the high, moderate and poor categories, most of the high-quality UGSs were found in Singapore compared to Sydney and Dhaka. On the other hand, there was no high-quality UGS in Dhaka. The UGS quality score in Singapore was significantly higher and significantly lower in Dhaka compared to Sydney. When the individual quality domain was modelled, the UGS in Singapore had statistically significant higher scores in the accessibility, safety, and landscape quality domain than Sydney. On the other hand, activity space score in Dhaka is significantly lower than in Sydney. Availability of ageing friendly features such as bike routes, fitness stations, useable benches, picnic facilities, trail and absence of incompatibility issues (e.g. poor maintenance) were significantly higher in Singapore than two other cities. Based on our sample data, socioeconomic inequity of the UGS quality inconsistently found a tendency of having higher quality UGS in the advantaged communities within all the three cities. Especially, inequities within the cities were found more in the amenities and landscape quality domains. There is no direct or moderating effect of neighbourhood ageing profile found on the UGS quality. The largeness of the UGS was found to be an important predictor of UGS quality except in Singapore, where the size of the UGS did not confound the quality score. Further investigations suggest that the ageing relevant total quality of the UGS was associated with sedentary and walking activities after adjusting the differences of cities. Sedentary and walking types of activities were significantly associated with only safety scores when individual quality domains were considered. On the other hand, vigorous activities of the ageing population had a statistically significant association with ageing relevant accessibility score, safety score and landscape quality score in the unadjusted models. The analysis ‘within city’ suggested that the ageing population in advantaged neighbourhoods with a higher percentage of the ageing population tend to participate more in different activities in Sydney and Dhaka, but not in Singapore. Discussions: The inequity in the UGS quantity and quality was resulted from differences in urban planning processes as well as how the UGS measures in each city were computed. These findings suggest that neighbourhood UGS quality is associated with different level of recreation activities, though not in a similar way everywhere nor every aspect of the quality is equally important. However, some of the results were counterintuitive. For example, the negative association between activity space score and vigorous activities and vigorous activities in Singapore; and the negative association between safety score and level of vigorous activities in Dhaka. Also, the socioeconomic inequity, as found in the UGS quantity and quality is not universal and these differences in part driven by the differences in the urban planning and public health promotion realm. The study findings also suggest that there is room for improving UGS quality, revitalising existing UGS for the promotion of social and active ageing. Especially, the evidence from Singapore suggests that strong commitment and careful urban planning can reduce inequality of health-promoting resources like parks and open spaces while keeping balance between population density and supplying quality UGS
