The vibration health risk assessment on operators of different capacity dumpers at opencast mine in India

In a labour intensive sector, some of the factors in the work environment which impact the health of vehicle operators include: Whole-Body Vibration (WBV) and Hand-Arm Vibration (HAV). The vibrations transferred from the dumpers are harmful to the operators; hence a study was carried out to measure the vibration from dumpers and its effect on operators in Indian opencast mines. Dumper is a vehicle designed to transport bulk material and used extensively in the construction and mining industries. For the measurement, dumpers with the different capacities were selected from the opencast mines. Vibration measurements were carried out in accordance with ISO 5349-1 for the measurement of HAV and ISO 2631-1 for the measurement of WBV. The obtained WBV exposure result shows that the problem of musculoskeletal disorder was significantly higher with respect to VDV(8) (69 %) in the exposed population as compared to A(8) r.m.s. acceleration (46 %). Moreover different capacity dumper vehicle hand transmitted vibration through steering wheel, A(8) r.m.s. acceleration observed in the range of 1.91 m/s2-4.28 m/s2. As per EU DIRECTIVE 2002/44/EC, specified Exposure Action Value (EAV) 71 % measured A(8) value falls within EAV limit. However, despite of the result operator experience problem of hand arm vibration syndrome. Hence there is a need of ergonometric deign enhancement on dumpers vehicle’s seat and steering wheel

Experimental investigation on flow induced vibration excitation in the elastically mounted square cylinders

In this paper an experimental investigation is performed on a range of transverse gap ratios (0.5≤T/D≤4.5) between the cylinders arranged in side by side configuration. The pattern of the test cylinder motion, spectral diagram and amplitude are used to analyze the vibration excitation at different conditions such as free stream velocity, natural frequency of the test cylinder. From the results, for the spacing ratio of T/D= 0.5 it is observed that the cylinders gets excited beyond the critical velocity and vibrates in a spiral pattern with the line dominated spectrum, which implies that by having a similar frequency along with a phase shift, the characteristics behavior of the cylinder is observed to be like an oscillator with the cross wise and stream wise response. Besides that, it is also observed that the cylinders at higher spacing ratios (T/D= 4.5) producing minimum oscillation when compared to the smaller spacing ratios

Accuracy of Short-Term Noise Monitoring Strategy in Comparison to Long-Term Noise Monitoring Strategy

The present study compares the accuracy in short-term noise monitoring strategies in comparison to the long-term monitoring strategies. The difference in short-term strategies from the annual average yearly sound levels is quantified as an error. The study extends the previous work reported exclusively for silence, industrial, commercial and residential zones in Indian scenario. The study re-affirms that random two months’ strategy is the Best Practicable and Economic Option (BPEO), whereby an error of ± 2 dB is observed with a probability of 95% approximately. Adopting long-term noise monitoring strategy in larger parts of Indian cities is cumbersome and expensive process. Thus adoption of random two months’ strategy adopted exclusively for silence, industrial, commercial and residential zones can be a practicable and economical option for noise mapping of larger parts of Indian cities

Estimation of uncertainty of effective area of a pneumatic pressure reference standard using Monte Carlo method

The current paper presents a comparative investigation of the experimental as well as simulated evaluation of effective area and the associated uncertainties, of a pneumatic pressure reference standard (NPLI-4) of CSIR-National Physical Laboratory, India, (NPLI). The experimental evaluation has been compared to the simulated estimation of the effective area obtained through Monte Carlo method (MCM). The Monte Carlo method has been applied by taking fixed number of trials (FMCM) and also by trials chosen adaptively (AMCM). The measurement uncertainties have been calculated using the conventional method, i.e., law of propagation of uncertainty (LPU) as well as MCM. Experimentally, the NPLI-4 has cross-floated against our newly established pneumatic primary pressure standard (NPLI-P10), which is a large diameter piston gauge. An excellent agreement in effective area and measurement uncertainty has been observed between these approaches

Accuracy of Short-Term Noise Monitoring Strategy in Comparison to Long-Term Noise Monitoring Strategy

569-576The present study compares the accuracy in short-term noise monitoring strategies in comparison to the long-term monitoring strategies. The difference in short-term strategies from the annual average yearly sound levels is quantified as an error. The study extends the previous work reported exclusively for silence, industrial, commercial and residential zones in Indian scenario. The study re-affirms that random two months’ strategy is the Best Practicable and Economic Option (BPEO), whereby an error of ± 2 dB is observed with a probability of 95% approximately. Adopting long-term noise monitoring strategy in larger parts of Indian cities is cumbersome and expensive process. Thus adoption of random two months’ strategy adopted exclusively for silence, industrial, commercial and residential zones can be a practicable and economical option for noise mapping of larger parts of Indian cities

Effect of post-welding heat treatment on mechanical properties of butt FSW joints in high strength aluminium alloys

381-388The friction stir welding (FSW) is a solid state welding process for joining two dissimilar metals using non consumable tools. This paper deals with experimental investigation on the effect of post welded heat treatment on mechanical properties of butt joint using FSW in aluminium alloys 2024 T6 (soft metal) and 7075 T6 (hard metal). In the post weld treated joint, the increase in hardness homogeneity is analysed in the nugget zone along the profile using micro hardness profile measurement. When the hardness homogeneity is attained, fracture occurs in nugget zone. The butt FSW joint after post welding heat treatment at low temperatures (200°C and 300°C) have tensile properties comparable with the FSW joints and fracture occurs in base metal 7075 T6. In 50% of FSW joints, deformation occurs after heat treatment at low temperature and also failure occurs inside stir zone. This work reveals that the progressive changes in the grain size and morphology in higher temperature post weld heat treated joint owing to abnormal grain growth (AGG) in the stir zone

A comparative investigation of pressure distortion coefficient of a pneumatic piston gauge and its associated uncertainty using varied approaches

This paper reports the evaluation of the measurement uncertainty of the pressure distortion coefficient () of a piston gauge using the Monte Carlo method (MCM) and its comparison with results obtained from the GUM (Guide to the expression of Uncertainty in Measurement) approach using the law of propagation of uncertainty. A reference pressure standard NPLI-4 was cross-floated against our pneumatic primary pressure standard NPLI-10, which is a large diameter piston gauge. The MCM was used for the simulated estimation. A good agreement is observed between the two methodologies, and the results are discussed in detail

Heat transfer intensification by Nanofluids- an Outline

711-712Nanofluids is a new benevolent of heat transfer medium, containing nanoparticles (1–100 nm)which are consistently and sturdily distributed in a base fluid such as<span style="color:#231F20; mso-bidi-font-style:italic"> water, ethylene glycol, methanol or oil. Nanofluids have been well-thought-out for applications as heat transfer fluids for virtually twofold decades. In this article, a brief outline has been accessible to allocate the unique features of nanofluids, their promising synthetic ways, and different thermal conductivity enhancement levels of heat transfer by nanofluid. </span