Public Sentiment Analysis and Topic Modeling Regarding COVID-19’s Three Waves of Total Lockdown: A Case Study on Movement Control Order in Malaysia

[Abstract] The COVID-19 pandemic has affected many aspects of human life. The pandemic not only caused millions of fatalities and problems but also changed public sentiment and behavior. Owing to the magnitude of this pandemic, governments worldwide adopted full lockdown measures that attracted much discussion on social media platforms. To investigate the effects of these lockdown measures, this study performed sentiment analysis and latent Dirichlet allocation topic modeling on textual data from Twitter published during the three lockdown waves in Malaysia between 2020 and 2021. Three lockdown measures were identified, the related data for the first two weeks of each lockdown were collected and analysed to understand the public sentiment. The changes between these lockdowns were identified, and the latent topics were highlighted. Most of the public sentiment focused on the first lockdown as reflected in the large number of latent topics generated during this period. The overall sentiment for each lockdown was mostly positive, followed by neutral and then negative. Topic modelling results identified staying at home, quarantine and lockdown as the main aspects of discussion for the first lockdown, whilst importance of health measures and government efforts were the main aspects for the second and third lockdowns. Governments may utilise these findings to understand public sentiment and to formulate precautionary measures that can assure the safety of their citizens and tend to their most pressing problems. These results also highlight the importance of positive messaging during difficult times, establishing digital interventions and formulating new policies to improve the reaction of the public to emergency situations.Taiwan. Ministry of Science and Technology; 108-2511-H-224-007-MY

Study of a variable geometry radial inflow turbine

SIGLELD:D47090:83 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Fabrication of tapered fiber based ring resonator

Tapered fiber based ring resonators are fabricated and its optical characteristic is investigated in detail. The ring resonator is fabricated by coiling the tapered fiber, which is firstly made by heating and stretching a piece of optical fiber, after the polymer protective cladding has been removed The comb filter with a constant free spectral range (FSR) and the maximum extinction ratio of 4.2 dB is achieved by a single-mode fiber based ring resonator. The FSR of ring resonator can be adjusted by controlling the diameter of the ring. The extinction ratio is improved in the polarization maintaining fiber based ring resonator where the maximum extinction ratio of 14 dB is achieved at 1531 nm region

Inline microfiber Mach–Zehnder interferometer for high temperature sensing

A compact inline microfiber Mach–Zehnder interferometer (MMZI) is proposed for high temperature sensing. The MMZI is fabricated using a flame-brushing technique in which both transition parts of a microfiber are tapered to reduce the waist diameter and form an interference region. Since the refractive index of the fiber core exhibits a different temperaturencoefficient from that of air, the interferometer is sensitive to temperature variation. The temperature sensitivity of the device with a length of 40 mm was measured to be 13.4 pm/°C with an excellent linearity for temperature measurement up to 800 °C

A Comparative Study of the Photostabilization of Polyvinyl Chloride with Nano and Micro Nickel Oxide

        تم  تصنيع الجسيمات النانوية NiO بالطريقة الكيميائية وشخصت باستعمال  بـ XRD  واتضح ان المادة النانوية بحجم بلوري (11.72 نانومتر) وحجم حبيبي (13 نانومتر) من  خلال صورة FESEM وايضااستخدم NiO micro ،استعمل كلا الاوكسيدين لتقييم إمكانية البوليمرات على  التحلل الضوئي ، تم فحص التطبيق العملي للتحلل التحفيزي للطور الصلب للبولي فينيل كلوريد (أفلام مركب PVC- NiO).  حيث يؤثر PVC سلبًا على البيئة لأن البوليمر الخاص به يتحلل ببطء ولكن له استخدام صناعي واسع والكمية المستهلكة لا تظهر أي علامات على التباطؤ في الاستخدام ، وبالتالي ، تمت دراسة توليف PVC- NiO micro and nano المعدل مع 0 ، 50 ، 100 و 150 و 200 و 250 و 300 (ساعة) كوقت تشعيع وعدد من التحليلات الطيفية. المتضمنه FTIR ,UV-VIS وتم فحص تأثيرات إضافة الاوكسيد النانويي والمايكروي إلى سلاسل PVC على اختبار الثبات البصري من خلال المؤشرات (ICO و IPO و IOH) وقياسات فقدان الوزن والأشعة فوق البنفسجية واللزوجة ، وكلها أظهرت أن مادة PVC المطورة تؤدي إلى ثبات البوليمرلفترة طويلة.  NiO nanoparticle synthesis by chemical method and characterized by XRD with crystal size 11.72 nm and grain size 13 nm from FESEM image also NiO micro used ,two NiO as an additive to evaluate the possibility of producing photodegradable polymers, the practical application of solid-phase photocatalytic degradation of polyvinyl chloride (PVC- NiO composite films) was investigated. PVC has a negative impact on the environment since its polymer degrades slowly, yet it has a wide range of industrial applications and the amount used shows no evidence of diminishing use. Thus, a synthesis of modified PVC- NiO micro and nano has been studied with 0, 50, 100, 150, 200, 250, and 300 (hours) as irradiation time and a number of spectroscopic analyses such as FTIR and UV-VIS. Additionally, the effects of adding nanostructures to PVC chains on optical stability testing procedures were examined through indices (ICO, IPO, and IOH), weight loss measurements, UV and viscosity

Current sensor based on inline microfiber Mach–Zehnder interferometer

A compact inline microfiber Mach–Zehnder interferometer (MMZI) is proposed for current sensor application. The MMZI is fabricated using flame-brushing technique where both transition parts of a microfiber are tapered to reduce the waist diameter and form an interference region. The fabricated MMZI shows a good interference fringes with a high extinction ratio of 15 dB. The fringe spacing can be tuned from 3.95 nm to 3.36 nm as the length of the interference region is varied from 4.5 mm to 6 mm. The shift in the interference fringes is observed to be linearly proportional to the square of the amount of the flowing current and the slope efficiency of the sensor is obtained at 140.26 pm/A² with a correlation coefficient of 0.99. Since the refractive index of the fiber core has a different temperature coefficient than that of air, the interferometer can be used as a current sensor by placing the current carrying wire in contact with the waist region of the second part of the tapered fiber

Micro-Ball Lensed Fiber-Based Glucose Sensor

The compact micro-ball lens structure fabricated at the cleaved tip of a microfiber coupler (MFC) is proposed and demonstrated for sensing various glucose concentrations in deionized water. The MFC was made by fusing and tapering two optical fibers using a flame brushing technique. It was then cleaved at the center of the minimum waist region to form a ball lens at the tip by an arcing technique using a fusion splicing machine. The proposed glucose sensor uses the micro-ball lensed fiber as a probe and a mirror as a target. The working mechanism of this device is based on the observed reduction in the peak power of the sensor wavelength spectrum as the concentration of glucose is increased. For a concentration change from 0 to 12 volume%, the ouput intensity of the sensor decreases linearly from -57.4 to -60.5 dBm with a sensitivity of 0.26 dB/% and a linearity of more than 99%

A new compact micro-ball lens structure at the cleaved tip of microfiber coupler for displacement sensing

A compact micro-ball lens structure is fabricated at the cleaved tip of microfiber coupler (MFC) waist for displacement sensor application. The MFC is made by fusing and tapering two optical fibers using a flame brushing technique. It is then cleaved at the center of the minimum waist region. Then a micro-ball lens is formed at the tip of the microfiber by an arcing technique using a fusion splicing machine. The proposed displacement sensor uses the micro-ball lens as a probe and a reflector as a target. As the target is moved from the micro-ball lens, an interference fringe is obtained due to the interference between two reflected beams from the micro-ball lens and the reflector. At the smallest displacement of 0.6 mm, the output spectrum shows the interference fringes with highest extinction ratio and largest free spectral range (FSR). Both extinction ratio and FSR reduces following the power trend line with correlation coefficient of 0.99 as the displacement increases. The Q resonant factor of the comb spectrum increases from 1628 to 38,286 as the displacement increases from 0.6 to 3.6 mm

Demonstration of microfiber hybrid Mach–Zehnder and knot resonator structure

We demonstrate a microfiber hybrid structure consisting of a microfiber knot resonator (MKR) and a microfiber Mach–Zehnder interferometer (MMZI) by micro-manipulating a microfiber. The microfiber used has a waist diameter of 1 μm and is fabricated using a flame brush technique. The hybrid structure generates dual resonances spectrum, which combines a characteristic resonant of MKR and MMZI. The MMZI resonant exhibits a much higher free spectral range (FSR) of 3.1 nm with the extinction ratio of 3 dB. The MKR resonant has a FSR of 0.24 nm and extinction ratio of 5 dB

Design of multimode tapered fibre sensor for glucose detection

In this paper the comparison behaviour between a tapered silica Multi-Mode Fibre (MMF) and a Plastic Multi-Mode (PMM) fibre is proposed. The tapered silica MMF (tapered core and cladding) and PMM fibre (only core) sensors use a Tunable Laser Source (TLS) at 1550 nm and a yellow He-Ne laser at 594 nm as the sources for measuring the attenuation of the input signal when the sensor is being soaked into the glucose solution. From this work, the tapered PMM fibre performs better in terms of its linearity, and provides a reliable calibration graph of glucose concentration against output signal. It has a sensitivity of 0.0088 mV/% and an error of 2.6 percent with a resolution of 0.36%. The tapered silica MMF has a better sensitivity, error and a better resolution but a lesser degree of linearity