Mekanik dan gelombang

Buku ini membincanqkan tentang perkara-perkara asas fjzik yang bertujuan memudahkan pelajar rnenqikuti pembelajaran yang terkandung di dalamnya seperti kalkulus dan aljabar vektor serta pelbagai sistem koordinat. Perbincangan juga menyentuh tentang mekanik Newton zarah tunggal di dalam satu, dua dan tiga dimensi, gerakan-gerakan ayunan harmoni terlembap dan pacuan, serta sistem zarah dan jasad tegar. Mekanik terkini berkenaan dengan formulasi secara Lagrange dan Hamilton juga dibincangkan serta diperteguh dengan pelbagai contoh. Di akhir buku ini pengarang memfokus kepada gelombang-gelombang tak sebar dalam fizik

The variation of optical absorption edge with sintering time for the ceramic ZnO + xMnO2-Bi2O3-TiO2

Photopyroelectric spectroscopy is used to study the variation of optical absorption of the ceramic xMn02 - 0.4 Bi2O3 - 0.4 TiO2 - ZnO, x = 0, 0.4 mol% sintered for 1-4 hours at the isothermal temperature, 1220°C. The wavelength of incident light, modulated at 12 Hz, is kept in the range 310 to 810 nm. The band-gap energy is reduced from 3.2 eV (for pure ZnO) to 2.83 eV for 0 mol% MnO2 for 1 hour sintering time and decreases further with the further increase of sintering time. Eg is decreased to 2.39 eV for 1 hour sintering time after the addition of 0.4 mol% of MnO2 in the ceramic combination. It is reduced to a value 1.9 eV with the further increase of sintering time. The variation of steepness factor σA and σB which characterizes the slop of exponential optical absorption, is correlated with the variation of Eg, sintering time and doping of MnO2. Microstructure and compositional analysis of the selected areas are analyzed using SEM and EDAX

Measuring Nanofluid Thermal Diffusivity and Thermal Effusivity: The Reliability of the Photopyroelectric Technique

It is important to study nanofluids to understand their extraordinary thermal properties and how the size, concentration and agglomeration of the nanoparticles affect those properties. Photopyroelectric (PPE) technique has been well established in the use of non-destructive measurement of thermal diffusivity and thermal effusivity, by using polyvinylidene fluoride (PVDF) films as sensitive pyroelectric sensors in thermally thick conditions instead of using very thick ceramic sensors. There have been two proposed practical configurations for the PPE technique, the back and the front PPE configurations, to obtain both the thermal diffusivity and effusivity, which are suitable thermal parameters of materials. This PPE technique involves the measurement of thermal waves in the sample due to absorption of optical radiation, by placing a pyroelectric sensor in thermal contact with the sample. This chapter provides a review of the back and the front PPE configurations to determine the thermal diffusivity and effusivity of nanofluids, sample preparation techniques using high-amplitude ultrasonic dispersion and data analysis for metal oxide-based nanofluid materials

The generation of dual wavelength pulse fiber laser using fiber bragg grating

A stable simple generation of dual wavelength pulse fiber laser on experimental method is proposed and demonstrated by using Figure eight circuit diagram. The generation of dual wavelength pulse fiber laser was proposed using fiber Bragg gratings (FBGs) with two different central wavelengths which are 1550 nm and 1560 nm. At 600 mA (27.78 dBm) of laser diode, the stability of dual wavelength pulse fiber laser appears on 1550 nm and 1560 nm with the respective peak powers of -54.03 dBm and -58.00 dBm. The wavelength spacing of the spectrum is about 10 nm while the signal noise to ratio (SNR) for both peaks are about 8.23 dBm and 9.67 dBm. In addition, the repetition rate is 2.878 MHz with corresponding pulse spacing of about 0.5 μs, is recorded

Effect of heat treatment on the optical properties of ceramic ZnO-MnO-Dy2O3.

Photopyroelectric spectroscopy is used to investigate the optical absorption behaviour of the ceramic composite (ZnO + 1 MnO + y Dy2O3), where y = 0 - 2 mol%. Ceramics were sintered at 1200 and 1300°C for 1 and 5 h. PPE spectrum with reference to the doping level and sintering time is discussed. Optical energy band-gap (Eg) is determined from the plot (ρhυ)2 vs hυ. It is found that the the value of Eg is reduced from 3.2 (pure ZnO) to 2.15 eV at the 0 mol% of Dy2O3 and is further reduced to 2.04 eV at the 2 mol% of Dy2O3 for 5 h sintering time at the 1300°C sintering temperature. Steepness factor σA and σB which characterizes the slope of exponential optical absorption is discussed with reference to the variation in the value of Eg. The phase constitution is determined by XRD analysis. Microstructure and compositional analysis are analyzed using SEM and EDAX. The maximum grain size and density of the ceramic were found to be 14 μm, 89%, respectively

Instructional Elements Assessments of Entrepreneurship Education in a Technical University in Malaysia

The technical and vocational education and training (TVET) program occupies the national education system to allow the students to learn practical, hands-on skills aligned with the industries' needs, ultimately preparing the students for the inexorable integration of technology brought about by the Fourth Industrial Revolution (IR 4.0). The rapid pace of change and broad impacts featuring IR 4.0 demand specific critical thinking skills, creativity, and readiness for risks, the qualities that are connected to entrepreneurship. Thus, it clarifies offering entrepreneurship education (EE) alongside a TVET program. There are arguments that EE is poorly embedded into the TVET program in Malaysia. The instructional elements concerned with the content, techniques, and activities through which students engage in creating entrepreneurial knowledge and value are considered essential for EE's success in a TVET program. This study assesses the state of instructional elements (i.e. content, teaching methods, infrastructure facilities, and learning assessments) of EE offered within a TVET program in Malaysia. Data were obtained from 37 students of a private technical university in Malaysia who enrolled for their entrepreneurship course through a series of group interviews. The study enlightens a few meaningful findings to propagate the entrepreneurial culture within a TVET program: (1) the content should be tailored to the readiness of the students, (2) action-based teaching methods should be engaged, (3) prior entrepreneurship experience should be specified for the entrepreneurship lecturer; (4) presence of ideal infrastructure facilities, and (5) learning assessments must be focusing in developing attributes of entrepreneurs

Photothermal affects our live

The photothermal effect of solid was first discovered by Alexander Graham Bell in 1880 while its application on determining the type of gaseous was recognized in 1903. However the application on solid only began in 1973 after Parker discovered it accidently during the characterizing of gas with photoacoustic cell. Following this, the research activities on solid have exploded by its flexibility in photothermal detections and can be applied in various applications. Here the review on photothermal research activities on sample characterizing in UPM and others are presented. Also included are the future direction and challenges in photothermal research

Thermal-wave interferometry of gas-liquid applied to a thermal-wave resonator cavity technique

We propose the potential use of thermal-wave interferometry in measuring thermal diffusivities of two media with a thermal-wave resonator cavity technique. In the derived expression for a two-layer configuration, during cavity length probing of the upper medium, the physical and thermal properties of the lower medium were reasonably assumed to be independent of cavity length; hence each of the two slopes of signal versus cavity length actually determines the thermal diffusivity of the corresponding medium. In order to check the validity of the proposed model, we measure the thermal diffusivity of air and glycerol. A good linear relation of the amplitude and the phase with respect to cavity length in the thermally thick region of both media was observed, and the thermal diffusivities of air and glycerol obtained were close to the literature values. We suggest the potential application of thermal-wave resonator cavity technique to measure the thermal properties of a single-layer fluid in a general thermal condition where the advantage is that the signal-to-noise ratio is normally high compared to the thermally thick case. This can be achieved possibly by coating the pyroelectric transducer with a thermally thick solid material prior to any measurements

Degradation of high level m-cresol by zinc oxide as photocatalyst

In this study, the high concentration of m-cresol as a sample of organic pollutants was degraded in the presence of zinc oxide and UV irradiation during 6 h at laboratory scales. The amount of photocatalyst, pH and m-cresol concentration were considered as effective factors on the photodegradation. The demineralization of m-cresol was measured by UV–Vis spectrophotometry while the total organic carbon-analyzer was used to determine the mineralization. The ultrahigh performance LC was used to identify probable intermediates. The results showed optimum condition at pH 7–9, which is the natural pH of industrial wastewater. Moreover, 100% of m-cresol was removed after 5 h of irradiation time, which is quite significant. The detected intermediates were 3,5-hydroxytoluene, 2,5-hydroxy-benzaldehyde, and 3-hydroxy-benzaldehyde after 3 h of reaction time. Reusability of the photocatalyst showed insignificant reduction in the photo-catalytic performance. In conclusion, this investigation indicated high potential of zinc oxide suspension to remove high level concentration of m-cresol under UV irradiation

AI-Based Analytics for Hawkers Identification in Video Surveillance for Smart Community

Street hawking is a widespread phenomenon in urban areas globally, presenting challenges for local authorities such as traffic congestion, waste management, and negative impacts on the city's image. This research addresses key issues faced by authorities in managing hawkers, including the resistance to formalization, maintaining urban aesthetics, waste disposal, and understanding user preferences. The study investigates the performance of the You Only Look Once (YOLO) algorithm, utilizing Convolutional Neural Networks (CNN) for real-time object detection. To achieve thisobjective, the YOLOv5 algorithm is trained with a custom image dataset collected from the same camera along the street in the city area to detect five classes of objects, namely umbrella, table, stool, car, and people. Real images that were captured via camera and video surveillance were compiled as datasets which are then used to train and test the algorithm. The study aims to provide insights into the data collection process of hawkers along the street around the areas and the development of real-time hawker detection for the smart city application