MAPAN最新文献

In order to explore the deformation behaviour, tensile specimens of a cast Hadfield steel were prepared and elongated to a strain of 10%, 15% and 20%. Assuming that the materials obeys power law of strain hardening, the strain hardening exponent and strength coefficients were evaluated from log true stress vs. log true strain data. The samples were also prepared for electron backscattered diffraction to study the evolution of microstructure and texture and compared with the microstructural characteristics of undeformed samples. It was observed that the dislocation density increased with the plastic deformation from 10 to 15% strain due to increased twinning density but it decreased in the specimens tested to 20% of plastic strain due to dislocation annihilations and grain refinement by mechanical twinning. The nature of residual stress measured by using a XRD-sin²ψ method in the as-cast samples was observed to be tensile whereas, in the deformed specimens it was compressive and correlated with the microstructural characteristics of the samples. The measurement results of microhardness of the tested samples showed an increased hardness with higher strains due to formation of α-martensite phase within the matrix. It was observed that the results obtained for residual stress and microhardness are in sync with the microstructural findings.

Calibration of electrical safety analyzers (ESA) are critical for ensuring the safety of medical electrical equipment (MEE) such as syringe pumps, defibrillators, and electrosurgical units, as per international and national standards. Accurate calibration traceable to the international system of units (SI) is essential to validate the safety parameters measured by ESAs. This paper presents the estimation of the measurement uncertainty for the calibration of ESAs for the electrical parameters essential in performing the electrical safety testing on the medical electrical equipment. The uncertainty of the relevant parameters, (i) Resistance (1 Ω) in protective earth resistance test mode, (ii) AC voltage (1–250 V) in point-to-point test mode (iii) DC (10 µA-6.5 mA) & AC current (1000 µA -6.5 mA) in leakage current test mode and related sub modes, (iv) Insulation resistance voltage (250 V & 500 V) and (v) Insulation resistance (0.5–90 MΩ) in insulation resistance test modes and associated sub modes is evaluated and the expanded uncertainty evaluated is 0.001 Ω, 0.1 V, 0.1 µA to 0.01 mA, 1 µA to 0.01 mA, 0.01 V and 0.1 MΩ- 0.4 MΩ respectively. The electrical safety testing has been conducted on key biomedical equipment such as neonatal intensive care incubator, defibrillator and infusion pump and their electrical safety parameters measured using calibrated ESA have been found to be in concurrence with the international electrotechnical commission (IEC) 60601–1.

The year 2025 marks 150 years of the Metre Convention, an intergovernmental treaty that transformed global cooperation in measurement science and technology. Signed in 1875 by seventeen nations, the Convention created a shared foundation for accuracy in trade, industry, and research. This feature article examines India’s growing integration into this international framework, tracing its historical progress from metrication to active involvement in global metrological institutions. CSIR-National Physical Laboratory (CSIR-NPL), India’s National Metrology Institute (NMI), is steadily progressing towards the vision of Viksit Bharat, a developed and self-reliant India. The article emphasises the country’s longstanding dedication to developing a strong and forward-looking metrology system, vital for achieving scientific excellence, industrial innovation, effective policy-making, and sustainable economic growth. India’s journey in metrology is not just about adoption but also about emerging leadership in shaping the future of global measurement standards.

Solar PV plant integration into the grid boosts green energy generation, but it may also impact the grid supply power quality, transformer loading, and lifespan. This study develops a mathematical model that relates meteorological data (solar intensity and temperature) to the transformer loading and life through their impact on PV plant power output and grid supply power quality parameters (total harmonic distortion of current, ({text{TH}}{text{D}}_{text{i}}) & power factor, PF). The real-time data collection is done from a 33 kV grid-connected 100 kWp rooftop PV plant and its analysis show that during the peak summer season, the rise in PV module temperature (average: 11.89°C) causes a 5.8% increase in transformer loading. During the peak winter season, the low solar intensity becomes detrimental to ({text{TH}}{text{D}}_{text{i}}). The generation of high ({text{TH}}{text{D}}_{text{i}}) in winter (average: 32.26%), causes an increase in transformer loading up to 5.1%. The plant’s power factor (PF) also contributes to an increase in transformer loading; a reduction in PF to 0.81 (lagging) leads to an expected 10.10% increase in transformer loading. These small increases in transformer loading may collectively reduce the transformer life.

The physicochemical and optical attributes of aerosols (PM₁₀) in the Delhi, National Physical Laboratory (NPL) [28.70°N; 77.10°E] region were examined during Biomass Burning (BB) and Subsequent Hudhud Cyclone (HC) in October 2014. Advanced offline characterization techniques, including Scanning Electron Microscope coupled with Energy Dispersive X-ray spectroscopy (SEM–EDS) and Wavelength Dispersive X-ray Fluorescence Spectroscopy (WD-XRF), were employed to probe particle morphology and chemical composition. Vertical profile data was obtained utilizing a dual-polarized micro-pulse lidar (MPL) system stationed at NPL. SEM–EDS analysis revealed the prevalence of carbon-rich spherical/core–shell aerosol particles attributed to the long-range transportation from BB activities in Punjab and Haryana. Frequency distribution analysis of the Aspect Ratio (AR), indicative of particle non-sphericity, shows that the majority of particles (~ 65%) fell within the AR range of 1.0–1.2, confirming the predominance of spherical/smooth particles during BB. During the HC, these particles transformed into non-spherical shapes upon mingling with moisture-laden sea aerosol spray particles predominantly composed of sea salts, exhibiting frequency distributions with peaks at AR range > 1.2–1.4 and > 1.6–1.8, and demonstrating a higher LDR value of ~ 4.7% (relative to ~ 3.7% during BB). WD-XRF analysis corroborated these findings, revealing an increase in Na and Cl element concentrations (avg.) from 6.54 to 7.52% and 0.63 to 1.03%, respectively, during the HC. Aerosol backscatter coefficient (ABC) values at 1.5 km (relative to that of lower altitudes i.e., 1 and 0.5 km) altitude during the HC were observed to be increased i.e., 0.052 km⁻¹sr⁻¹ owing to the predominance of particles with sea origins.

In order to study the burning explosion power characteristics of different dry-type bushings, the burning explosion experiments of resin-impregnated fiber bushing and resin-impregnated paper bushing under 10 kV ultra-high voltages were carried out. The power parameters such as burning explosion pressure, fragment velocity, and temperature were tested, and the explosion power of the bushings was quantitatively evaluated. The results showed that the time-history curves of bushing explosion pressure all show two peaks, and there is a time difference between the two energy releases. In the same radius, the maximum explosion pressure of the fiber bushing is higher than that of the paper bushing by 34%-49%. For the fiber bushing, the first pressure peak is largest in the different radius range, but the first peak of the paper bushing is about half of the second peak, and the pressure duration is only half of the fiber bushing. The pressure propagation speeds of the fiber bushing and paper bushing are 380 m/s and 452 m/s, respectively. When the fiber bushing explodes, the average velocity of the fragments in the direction of the jet orifice is 94 m/s, and the velocity of the fragments is only 10 m/s in the direction away from the jet orifice. The fragment velocity in different directions is basically the same for the paper bushing is about 50 m/s at a radius of 3 m. The temperature rises rapidly when the fiber bushing explodes and continues for a long time when it is reduced to about 3000 K. The time history curve of the temperature of the paper bushing shows an upward-downward-upward trend. The maximum temperature of the fiber bushing is 5399 K, which is higher than that of the paper bushing by 724 K.

This study proposes a novel online monitoring system for chatter vibration detection in milling processes, utilizing the Variational Mode Decomposition (VMD) technique in conjunction with Spectral Entropy. VMD, an advanced and robust signal processing method, is employed to decompose audio signals captured during milling into Intrinsic Mode Functions (IMFs), enabling the analysis of complex signal patterns. Controlled milling experiments were conducted by varying key cutting parameters, and the signals were processed to extract 16 statistical features, including Root Mean Square (RMS), Waveform Index, Skewness Index, Crest Factor, Log Energy Entropy, Power Spectral Entropy, Spectral Entropy, and Log Detector. Among these features, Spectral Entropy demonstrated superior predictive capabilities in distinguishing chatter conditions—stable, transient, and unstable states. For classification, multiple machine learning models were applied, including Random Forest, J48 Decision Tree, and REP Tree classifiers. The J48 classifier achieved the highest accuracy of 86.11%, followed by the REP Tree classifier with 82.22%, and the Random Forest classifier with 81.11%. These results highlight the effectiveness of the J48 classifier in providing precise and reliable classification of chatter states. The proposed approach significantly contributes to the development of an effective real-time chatter vibration monitoring system, enhancing diagnostic accuracy and offering innovative solutions for improving machining operations.

This research examines the transformative impact of synthetic lubricants, particularly polyglycol-based oils, on the operational efficiency of screw compressors, emphasising the advancement of sustainable industrial practices. The synthetic oil, noted for its superior oxidation stability, prolongs oil change intervals and enhances the longevity of filters and separators. The integration of specialised inhibitors guarantees the preservation of internal compressor cleanliness, resulting in continued high efficiency. Experimental investigations comparing synthetic polyglycol oil to conventional mineral oil in screw compressors indicate substantial enhancements in overall efficiency. The synthetic oil offers extended maintenance intervals, achieving up to 8,000 operating hours in oil-injected screw-type compressors and 40,000 operating hours in turbocompressors, alongside prolonged filter and separator lifespans and diminished cleaning expenses due to its exceptional dirt-dissolving properties. Additionally, the synthetic oil aids in sustaining low oil vapour levels in compressed air, minimising oil use, and averting the gumming of pneumatic valves. The synthetic oil adheres to industrial requirements (DIN 51506-VDL and ISO 6743-3 L-DAJ) and demonstrates outstanding wear prevention for steel friction components. Possessing a kinematic viscosity of 55 mm(^{2})/sec at 40 (^{circ })C, it exceeds bearing life specifications, hence forming an efficient lubricating coating for anti-friction bearings. The study highlights the considerable potential of sustainable lubricants, especially polyglycol-based oils, in improving efficiency and reinforcing the environmental sustainability of screw compressors. This study offers significant insights into the practical applications of synthetic lubricants in industrial settings, highlighting polyglycol-based oils as a viable solution for enhancing screw compressor technology. The study elucidates a vital element of sustainable materials within the industrial sector, providing an in-depth comprehension of their influence on machinery efficacy.

The present study reports the airborne sound insulation and absorption characteristics of noise barriers and acoustical facades tested in reverberation chambers. These materials were fabricated from the sandwich partition panels and masonry structure for noise control. The study presents the rarely reported sound insulation and absorption properties of wide kinds of sandwich and masonry constructions used as noise barriers. The sound insulation characteristics of metallic, polycarbonate sheets (transparent/opaque), composite fiber cement boards, AAC blocks, green materials, facade glass, and other distinct materials are presented for their applications either as noise barriers or acoustical facades in buildings exposed to higher noise levels. Also, the sound insulation as well as absorption performances of recycled plastic, polycarbonate and metallic material based noise barriers were evaluated. The study also presents the sound insulation characteristics of temporary noise barriers that can be useful for noise control at construction sites and sound absorption characteristics of metal absorptive noise barriers tested in reverberation chambers. The applications of the study may not be limited only to usability as a noise barrier but also to balcony treatments and facades. The rarely reported sound insulation and absorption characteristics of various materials discussed in the present study makes it indispensable for designers and consultants for developing noise barriers accomplishing the desired insertion loss characteristics.

The areal quantitative analysis of the surface texture is performed using non-contact type 3-D optical surface profilometer. The captured curved surface consists of macroscopic form, waviness, roughness, and system noise correspond to large, intermediate, small, and very small wavelength signal respectively. It is important to separate the roughness from the captured surface to measure the surface roughness of a component correctly and accurately. This paper presents a method to remove the form and filtering process of surface texture for areal surface roughness measurement according to ISO 25178-2:2021. The S-filter is used to remove the system noise with suitable nesting index resulting in primary surface. The F-operator is applied to the primary surface to remove the form error by fitting the suitable polynomial which results in the S-F surface. Further, The L-filter is applied to the S-F surface to get the areal roughness surface. Additionally, these processes are explained using Zygo Mx software by considering some surface geometries such as spherical, cylindrical, and freeform.